When I first wrote this article six or seven years ago, it was for my local BlueTec diesel owners.    I just wanted to keep them informed about the issues & problems associated with Mercedes-Benz BlueTec Diesel engines.    I had no idea that it would turn into a global source for BlueTec information.   I thought if my customers understood how a BlueTec diesel worked, they would be more proactive on preventive maintenance.     I first had to convince owners that the Mercedes-Benz dealer wasn’t telling them what the factory actually recommended.    Dealers were telling BlueTec owners they could go ten & twenty thousand miles between oil changes.    At best, this was a half truth.    What the factory actually says, is that ten or twenty thousand mile oil changes is under “ideal conditions”.   Mercedes defines “ideal conditions” as constant freeway driving.     Wait a second.    Practically no one drives exclusively on the freeway.    Why were Mercedes-Benz dealers tell their customers something that would ruin their engine?   If a BlueTec diesel is driven on short trips in stop & go traffic, the factory said the oil changes should be “substantially reduced”.    Down to five thousand miles…. 3000 miles if the engine idles a lot.    I had owners tell me that the dealer refused to change the oil any sooner than 20000 miles.     As the engines kept locking-up, no one bothered to read what Mercedes-Benz actually said about the oil changes.    So in May of 2012, the factory sent dealers another Service Bulletin, SI00.20-D-0029A.     This bulletin clearly explained the oil change intervals.    It also explained fuel dilution, & precisely how so much diesel fuel ends up in the crankcase oil.     The factory even told dealers if the reduced service intervals were not strictly adhered to, Mercedes-Benz would not warranty the engine damage.    How much plainer could they make it?    So why do dealers, even to this day, ignore what the factory tells them?    When regeneration of the DPF occurs,  excess fuel washes past the piston rings & into the crankcase.    The factory clearly told dealers; short trips cause the regeneration of the DPF to be interrupted.     When the regeneration is interrupted,  excess diesel fuel is dumped into the crankcase, & the DPF is not cleaned.    As the miles pile up, the engine gets deeper into trouble.    Finally, the engine locks up, & nobody knows why?    The factory told dealers they should explain this to their BlueTec customers & to recommend that owners drive their vehicle on the freeway for 30 minutes to allow complete regeneration of the DPF.     So what happened?    Why didn’t dealers tell owners what the factory actually recommended?    
Now new owners stumble onto this website after they bought a BlueTec.     Someone told them about the BlueTec diesel problems, & it’s “Oh no, what have I gotten myself into?”    The original BlueTec owners are mostly gone.    Their engines locked up years ago.     Mercedes dropped the BlueTec SUV’s from their new car line-up.    Older BlueTec SUV’s have lost most of their resale value.    When a owner gets a $5000 or $6000 estimate, they dump the vehicle.    However, Sprinters continue to use the same BlueTec diesel that went into Mercedes SUV’s.     Sprinters are very popular, & they hold their resale value.    If someone explains it in plain English, Sprinter owners will actually do the maintenance.

As the BlueTec market matures & evolves, about 25% of the calls I get, are coming from people who have ordered or want to buy a new Sprinter CDI.   They’re not sure what they’re getting themselves into.    This brings up a really good opportunity, that really wasn’t’ a factor before now.   In the past, I was dealing with owners who were already in trouble or close to it, so what was the point of telling them what they should have done when it was new.   Since things are different now, I’ll start at the very beginning of a BlueTec’s life & explain the golden opportunity you don’t want to let slip away.  
You’ve taken delivery of your new Sprinter & you want to head home so you can show your family just how cool the Sprinter really is.    It’s time for a “Road Trip”!    Nobody wants to think about preventive maintenance; it’s brand new.   And I might add, it will only be brand new once.   You certainly don’t want somebody telling you about the trouble that’s just started.   “Can’t I just enjoy it for 24 hours before someone starts yapping at me?”    No, & here’s why.    Mercedes-Benz filled your new engine with 5W/30 Mobil One ESP synthetic motor oil.    Ask any engine builder what happens when you try to break-in a new engine with synthetic oil.    I can hear the nay sayers now.    “New engines are built with tighter tolerances & don’t need to be “broken-in” like engines in the past.”   “I’m living in the dark ages.”    I know all the arguments for no longer breaking-in modern engines.   Here’s why they’re wrong when it comes to a BlueTec diesel.    It is critical for diesel piston rings to be properly mated to the cylinder walls.   Synthetic oil is to slippery to let the piston rings seat in.   If you start off with special “Break-in Oil” when the engine is new, the rings will form a nearly perfect seal with the cylinder walls.   This is far more important for a diesel for several reasons.    Diesels have twice the compression a gas engine has.   The better the piston rings seal against the cylinder walls, the less blow-by of compression gases into the crankcase.    This also increases oil consumption.    “But my engine doesn’t use any oil, so my piston rings must be perfectly mated to the cylinder walls.”   By Mercedes own admission, “Fuel Accretion” is a real problem for a BlueTec.   “Fuel Accretion” is when unburnt diesel fuel washes past the piston rings during the regeneration of the DPF.    Mercedes has to inject extra fuel to increase the exhaust temperature to 1600F in order to burn off the soot trapped in the DPF.   If the piston rings are less than perfectly seated to the cylinder walls, unburnt diesel fuel washes past the rings & into the crankcase.   When you break-in the piston rings with synthetic oil & then go 10K or 20K until the first oil change, the piston rings are nowhere near a perfect sealing surface.    You think your engine doesn’t burn oil, because the oil is being replaced with diesel fuel.    Read it for yourself in the 2018 Sprinter Owners Booklet.   Mercedes-Benz explains how this happens.    So why doesn’t Mercedes-Benz use Break-in oil in new engines?    Because emission regulations & fuel economy standards.   All manufactures are heavily fined if they don’t comply with the fuel economy standards.     
If the piston rings were properly mated to the cylinder walls, the oil would stay in the crankcase, & the diesel fuel would stay in the combustion chamber.    From the drivers perspective, the result would be the same, no oil consumption.    But with a proper break-in, it’s for the right reason.    Now does it make sense?

A BlueTec diesel is the most complicated & least understood engine Mercedes-Benz makes.     The average mechanic hates working on them, because they are a guaranteed comeback with a mad customer.     It’s way easier to make money on other models.    Plus, Mercedes-Benz treats their BlueTec diesel mechanic’s like they’re the one’s who built this mess.    Where a owner lives & how they drive, makes a big difference in reliability.     One owner rarely has a problem, while the guy down the street is bouncing from shop to shop with nothing but huge repair bills to show for his effort.     How does that happen?     
This engine & its emission system is a lot like an onion.    Every time I thought I finally understood it, I discovered a new level of complexity.    Now, BlueTec owners around the world, have found my feeble attempt to explain the BlueTec diesel.    I’m told this article is causing quite a stir on various owner’s forums.    New owners go to a BlueTec forum & look for answers.    Suddenly they get blasted by the forum “know-it-all”.    It’s always the guy that knows just enough to sound like he might be right.    They actually sound like they work for a Mercedes dealership.     They claim there is nothing wrong with the BlueTec diesel, & the 10000 & 20000 mile oil changes are great.    They tell everyone they have 500000 miles on their BlueTec, & nothing has ever failed.     Odd, because Mercedes-Benz admits they have a 100% failure rate on a number of major systems.    Timing chains, turbochargers, oil coolers, SCR tanks, & Oil Separators to name a few.    I guess some people have all the luck.

A few years ago, my mechanic’s began to complain about all the phone calls from this article.    “Why are we answering phone calls from all over the country?”    “Let these people call their local Mercedes dealer to answer their diesel questions.”
They had a point, but I didn’t have the heart to take the article down.

Thankfully, after 50 years of Mercedes-Benz, I’ve retired.     I had the business phone number roll over to my cel phone, because I didn’t want to abandon my old customers.     But that also meant I kept getting dozens of phone calls every day about BlueTec diesels.      

Mercedes-Benz publishes a lot of technical information.    The problem is, it is not easy to find.     They have two technical websites for BlueTec information.    Www.startekinfo.com, & www.cvtekinfo.com.    Mercedes charges $60 per day for access to either of these websites.   These websites are hard to navigate.    Mercedes also publishes a lot of conflicting information.
BlueTec diesels are also installed in Dodge Vans, Freightliner Vans, & Jeeps.    It doesn’t matter what vehicle it’s in, a Mercedes-Benz BlueTec diesel works the same.    When Mercedes first came out with the OM642 diesel in 2007 & 2008, they called it a “BlueTec”.     It wasn’t.     “BlueTec” is the name of the emission system which has a DEF (Diesel Exhaust Fluid) tank.     Also known as “AdBlue”, or SCR (Selective Catalytic Reduction).     (Mercedes loves its acronyms.    For normal people who are not into all this tech stuff, I’ll try to explain them as I go along.)         2009, was the first year Mercedes-Benz actually had DEF fluid or AdBlue, injected into the exhaust.      They inject the DEF into the exhaust to reduce emissions.      Except for the DEF fluid, all OM642 V6 diesels operate the same way.     From day one, all OM642 diesel’s have a DPF, (Diesel Particulate Filter, which traps the black soot in the diesel exhaust).      The engine does not need the DEF or the DPF to operate.     “So why does the engine run to badly when something goes wrong with the DPF or DEF systems?”     When the DPF or DEF has a problem, the DPF or DEF computer tells the engine’s computer to stop running properly.   Mercedes calls this “Limp Home”.      When the engine computer (ECU) switches to “Limp Home”, it lacks power.     Warning lights go  on.     If you continue to ignore the warning lights, the ECU finally won’t allow the engine to start.        

All Mercedes diesels have exhaust driven, air / oil cooled Turbochargers, & air cooled Intercoolers.    Why is this important?     To give a engine more power, the Turbocharger forces more air into the combustion chamber.     That gives the engine more power.     The Intercooler’s job is to cool down the air going into the combustion chamber.    The Turbocharger is powered by hot exhaust gas.     The faster you accelerate, the more exhaust is created, & the more power the Turbocharge creates.     So why is this a problem?     The exhaust gas is real hot.     Remember the DPF?     Diesel engines have black soot in the exhaust.   Every so often, the engine has to burn off all the soot trapped in the DPF.     To do that, the ECU injects a lot more fuel to heat up the exhaust, & “regenerate” the DPF.    Think of it as a self cleaning oven, only hotter.   In fact, when you’re driving up a steep mountain & you’ve got your foot on the floor, the exhaust gas can also climb to over 1600F.      That means the exhaust gas is also heating your Turbocharge to over 1600F.      For anyone who doesn’t believe  the turbo runs that hot, I invite them to visit the Garrett Turbocharger FAQ website.   Garrett & two other companies make the Turbocharger’s for Mercedes-Benz.      Garrett explains that it’s normal for a Turbo like the one Mercedes put on the BlueTec diesel, to run at 1600F.     That also means your engine oil is also heating up to 1600F.     You would think that Mercedes-Benz would have thought of a better way to cool your Turbocharger?    Well, they actually did.    They just didn’t put it on your engine.    In fact, they put the cheapest, low end Turbocharger & Intercooler they could find, on your BlueTec diesel.     Garrett makes fabulous Turbochargers that are water cooled with special oil sumps to handle the extreme heat.    (No, you can’t retrofit a water cooled Turbo onto your engine.)    Your Turbocharger is lubricated & cooled with the same oil that’s inside your engine.     As soon as your engine oil enters your Turbocharger, it is super heated to a temperature far beyond what the oil was ever designed for.     Are you now starting to see why Mercedes is having so much trouble with the engine oil?   It doesn’t take long before all the oil in the engine is boiling hot.    High oil temperatures is not really a problem in gas engines.   But for exhaust driven turbocharged Diesel engines, extreme oil temperatures is now a problem.

So how do we solve the problems with the OM642 with the way it is?    I used to complain that Mercedes had stupid oil change intervals.    But actually, the document Mercedes-Benz published in 2012, explains the oil change intervals & these problems I’ve described; perfectly.    If they had insisted their dealers adhere to that document, they would have far fewer warranty claims.   They would have happy diesel owners with vehicles that retained their resale value.    Mercedes reputation would be far above where it is today.    Why did Mercedes-Benz let their dealers ignore the proper maintenance procedures?    Why didn’t the factory go to dealers & put their foot down, & insist they tell owners how to properly maintain a BlueTec diesel?   It’s simple, dealers wouldn’t sell as many new cars, if you’re driving your diesel for 30 years.   There are other reasons, but that one is good enough. 

Because of Mercedes new 2018 maintenance schedule, I’ve dropped my tedious explanation of diesel oil specifications.     It was just to confusing & it appears the EPA, Mercedes-Benz, & the oil companies now agree.     I don’t think they’ve officially given up on “low SAPS” diesel oil, but it appears they are ignoring their previous guidelines.    Whatever it is, something changed in 2018.       In the past, I recommended motorcycle oils because they were much better at dealing with extreme heat than “low SAPS” diesel oils.   Over the past year, a few new diesel oils have entered the market.   These new oils have very similar specs to the best motorcycle oils.   I’ve heard from a number of Petroleum engineers who have been gracious enough to share some of their technical articles.     One engineer sent me information about a new diesel oil with an extraordinary Material Data sheet.     Another Engineer sent me a redesigned billet OM642 & OM651 oil filter housing.    The new housing supports a much bigger spin-on Cummings or Duramax diesel oil filter.   It works best on the Sprinter, because there is more space to work with.      It is easy to install & it greatly improves oil filtration.     You can check it out at www.pktfilterinsert.ca.    However, if your engine is still covered by a Mercedes-Benz warranty, you can only use the genuine Mercedes-Benz oil filter.   Mercedes will void your warranty if you don’t use their oil filter.    Once the warranty is over, you can install the bigger oil filter housing.     

This article has taken on a life of its own.    Now that I’ve retired, I’m getting calls & emails from all over the world.     In this article I’ve tried to give owners a way to prevent problems.   A lot of owners have more questions or a specific problem.    BlueTec’s are not easy, & many owners don’t have access to reliable diesel service.     Even though Mercedes put the OM642 & OM651 in a lot of vehicles, I’m gradually hearing from more Sprinter owners.     Sprinter’s hold their resale value much better than anything else Mercedes-Benz sells.     Sprinter owners tend to be more proactive about their maintenance.     They use the Sprinter for work or for travel.      They’ve often invested a lot of money customizing their Sprinter.    Sprinter owners don’t have the luxury of walking away from their vehicle when they get hit with expensive repair bills.     Sprinters that have been converted into RV’s, have to be extremely reliable when they are far from home.   It’s not just the cost of the repairs, it’s the hassle of being stranded someplace.   If it’s a work vehicle, owners loose business when the Van is in the shop.    Sprinter owners also tend to be more concerned about the environment.     If the OM642 & OM651 are “properly” maintained, the emission system actually works.      Most owners don’t want to delete the emission systems.    They will spend a reasonable amount to keep it maintained.    But after a dealer hands them a $17000 bill for some rust in the fuel system, it gets hard to justify spending $5000 to replace the SCR system.    I know for a fact, this engine reacts well to good preventive maintenance.    The problem is, dealers don’t tell owners the proper way to maintain a OM642 or OM651 diesel.     Mercedes did a much better job explaining the maintenance in their 2018 Owners manual, but they are still a long way from the plain English the average owner needs.     Then you have dealers that still won’t change.    Every day, owners tell me their dealer is still telling them they can go 20000 miles on oil changes, & to use Mobil One 0W/30 ESP oil.    Owners tell me they show their dealer the 2018 Sprinter Owners Booklet, & their dealer refuses to believe what it says in the Owners Booklet.    This is beyond stupid.     

I’ve spent so many years helping people with these diesel problems, it’s hard to retire & just switch it off.     However, I can’t spend my retirement answering phone calls & emails.    I would rather spend my free time with my one & only Grandson.    I’m starting to like this Grandpa thing.   But then one of my old customer’s came up with a good idea.     I can still use my experience to help diesel owners & help my Grandson.     I don’t need the extra money.   I would rather have the free time.    But I’m highly motivated to see that my Grandson gets a college education.     I don’t think anyone will debate the value of a college education over the next 70 years.    In order to fund his college savings plan, I’m willing to help Mercedes diesel owner’s with their problems.    For a long time, I freely answered people’s questions & sent them as much technical information as they wanted.  People would call me with all sorts of questions.   This stuff is hard, & there is not much help out there.   I’m sympathetic, but I already did my 50 years.     If not for my Grandson, I would let the website expire.     So, for $200, I’ll help BlueTec diesel owners with their problems.     I’ll answer all your questions & send you a written plan with exactly what to do.   I originally thought I could do this on the honor system, but that didn’t work.    Some people sent me dozens of emails & phone calls.     They would send me their repair orders & estimates for thousands of dollars in repairs.    After spending many hours helping them sort through all of their problems; you guessed it, they forgot to send the money.     Then there are the guys who’ve taken their engine apart & can’t get it back together.      They want me to talk them through it.      They also forgot to send the money.     It went on & on late into the night, Saturday & Sundays included.      About half the people appreciated the help & sent the money.    Now I’ve set up a PayPal account to fund my Grandson’s college savings account.     If after reading this article, you want more help, you can email me at ‘tom54stephens@gmail.com’.     Let me know what your problem is.     Tell me where you live & how you drive.    Tell me your model & year.     How many miles & a brief service history.   I love hearing from people buying a new Sprinter.   I can show you how to make that thing bulletproof.     For $200, I’ll answer all your maintenance questions & send you all the technical data you could ever want.     I’ll explain it on the phone & email you all the instructions.   I want people to understand the complete picture, because it makes it easier to avoid expensive repairs.    All the horror stories you’ve read about, are totally avoidable.    You really can live with this engine, it takes knowledge.
I’ve tried to answer most of the typical questions in this article.    I’ll tell you where you can buy all the things you will need.      (By the way, I don’t make anything off of what I recommend.    I also don’t put any of those annoying Google Ads on the website.)      I’ll explain what oil to use for your specific situation.     There is no one oil that works for 100% of the vehicles.      If you’re having the early warning signs, I can tell you how to prevent a $30000 disaster.     There are other common failures that I can save you thousands even after it’s failed.     Because of the world we live in, there are a lot of things that I can’t put in this article.  
Proper maintenance is not cheap, but compared to the repair bills owners have sent me, maintenance is a bargain.    I want you to avoid being one of those You Tube video’s of Mercedes diesel problems.    Find a good mechanic & support him.    If you have a complicated problem that has bounced from dealer to dealer, I can diagnose the problem & tell you what has happened.    Some owners have problems that they’ve paid thousands of dollars & it’s still not fixed.   Most of the time, the solution is in the information I send owners.    If it’s something I’ve seen & I’ll explain what’s causing the problem.    Some owners have dozens of Repair Orders with long histories of questionable repairs.   Those can take a lot of time to wade through.    If you have one of those situations, tell me before we start, & we’ll talk about the cost.
I’ve spoken with a large number of owners & heard their stories about their experiences with their local Mercedes-Benz dealer.    It is shocking how little dealers know about this engine.   There are just to many stories, from all parts of the country.    There are certain big dealers that keep popping up with outrageous complaints.    Mercedes-Benz has to know this.
Dealers arbitrarily tell owners there are no software updates for their vehicle.   Mercedes-Benz knows how important the updates are.   They know exactly how many updates are needed & exactly how many are actually preformed.    I would be surprised if 5% of the updates are actually performed.    Every BlueTec diesel needs to have ALL of its software updated.    Only about 1/3 of the dealers have a mechanic that is capable of doing these updates.     The rest stumble along making excuses.    Mercedes sends out the bulletins, & dealers won’t read them.     Or they just don’t care.    

If you plan on driving a Mercedes-Benz vehicle with a OM642 or OM651 engine, you need to educate yourself on how this thing works.   If you don’t, you will pay dearly for someone else to stumble around under your hood.    Even if you educate yourself, it will still be very hard to find competent service.   If you find a consciences dealer or mechanic, count yourself as very lucky.    If you find a mechanic that can actually do the software updates, you need to grab hold of him, & not let go.

People have been told to protect the DPF at all cost.     The DPF is no big deal.     It can be cleaned or replaced.     The engine is a big deal.       The priorities are backwards.     I’m going to explain this, so it makes sense.    You won’t have to believe someone at the dealer who knows even less than you.     If you want to figure this out on your own, or let your dealer answer your questions; go right ahead.    You’ll not hurt my feelings.     If you think $200 is to much, you can spend a day on one of the Mercedes-Benz technical websites.    Knock yourself out.       If you think your BlueTec is confusing, wait until you waste a day on their website.       If you’re looking at a New Sprinter, I can tell you what options you’ll want & which ones you don’t.   For example, you don’t want Xenon headlights.   When they burn out, they can cost thousands to repair.     You can make the standard headlights just as bright as the factory xenon for a fraction of the cost.    I’ll explain the proper maintenance & what you can expect for problems.    A new Sprinter, is a darn nice vehicle.     If you start off with good maintenance, most owners are very happy with them.    However, these are complicated emission systems.   Some problems are inevitable.    If you’re the type of person that worries about every mechanical problem, you will not like a BlueTec Sprinter.    However, if you have a general grasp on how this thing works, little problems are not a deal breaker.     Valet or Shuttle companies love Sprinters, but they should actually avoid the BlueTec.   Why, Sprinters make perfect people haulers?    Drivers often let the engine idle for long periods to keep their customers cool or warm.    The drivers themselves, will set in the Van & let it idle while their passengers are attending some event.   Mercedes has hinted for years, that long idle times are bad for the engine.   Now they finally say it plainly in their 2018 Owners manual.    Idling & short trips are a huge problem for the BlueTec diesel.   Yet Mercedes sells the Sprinter Van to Fleet companies, knowing full well that they will have major problems.
If you are buying a new Sprinter with a BlueTec diesel, buy the maximum warranty offered.   You can only get the Genuine Mercedes-Benz warranty.    Service contract companies have been burnt so bad, they got out of the Diesel business.    Don’t buy a “Maintenance Contract”.    That’s pre-paid maintenance that can only be done at a dealer.   You’re locked into their recommended maintenance, like it or not.   Plus, it’s a lot more expensive.       Keep all your records.   Only use genuine Mercedes-Benz filters.   If you’re buying a motor home, only buy the Mercedes-Benz extended warranty.   Buy all the long distance towing coverage you can get.   I have no idea how a motor home dealer can diagnose problems with a Sprinter.   Mercedes dealers barely keep current with training.   I have no idea how a RV center can afford to send mechanics to all their different brands & buy the factory diagnostic equipment.   I hear from RV owners who wait days for a Mercedes-Benz dealer to even scan for fault codes when they are stranded out of town.   RV owners have spent a great deal of money & they have no idea how shallow the knowledge pool is at these RV centers.    If you plan on driving from Chicago to Seattle, you will cross a 1500 mile dead zone.   If you breakdown, you will have a very hard time finding a BlueTec mechanic.   It is way easier to start off doing the right maintenance on a Sprinter, than fight these problems on the open road.

.    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .    .

WHY IS EVERYONE SO UPSET WITH THE BLUETEC DIESEL?    Mercedes diesels have great power & excellent fuel economy.    Sprinters drive better than another Van on the market.    I love Sprinters.   The SUV BlueTec diesels….. not so much.    The SUV’s depreciate so fast, people are upside down & it’s hard to justify spending more money to save them.
On the other hand, Sprinters are unique in the marketplace.    They have long useful lives & are worth the investment.     I totally understand why people like Sprinters.     So why are there so many complaints?    Most people buy a BlueTec & they believed the salesman when he said they can go 500000 miles with no problems.     I’ll bet the salesman didn’t tell you Sprinters take special maintenance & special mechanics to work on them.     The average owner is not prepared for the maintenance cost & the aggravation.
A BlueTec diesel is way more complicated than any other Mercedes made.     Routine maintenance is more expensive.     Any mechanic that truly understands a BlueTec is extremely skilled.     He is typically the smartest guy in the shop.     If you find a good BlueTec mechanic, he’s good as gold.     But even the very best BlueTec diesel mechanic will have comebacks.      Most dealer mechanics won’t work on a BlueTec because they can make more money working on easier models.      Who needs to listen to mad customers blaming them for inherent design problems that aren’t the mechanics fault.
At first, proper maintenance seems like it’s to expensive.      I can assure you, it’s way less expensive than a new engine.    

I see so much misinformation about motor oil, is no wonder owners don’t know what to do.   I watched a YouTube video the other day, & the oil expert started out by telling everyone to follow the manufacture’s recommendation.   He left out so many important facts, I don’t know what qualified him as a expert.    He started out telling his viewers, they were being scammed by their repair shops.    He said the shops were telling owners to change their oil to often.   He said nothing about the CAFE fuel economy standards & how they effect motor oil.    What’s in the Owners manual is not the manufactures recommendation, it’s what the EPA wants.    Motor oil is now part of the EPA’s plans to reduce air pollution.   The EPA forces manufactures to “recommend” certain oils that improve fuel economy.   What the oil expert was telling people was a over simplification.    If manufactures don’t meet the EPA’s strict fuel economy standards, they face heavy fines from the government.    To meet those fuel economy standards, oil must have a very thin viscosity.   0W/20 is common & 0w/16 is under development.    Everyone wants better fuel economy, so what’s the problem?    When it comes to a BlueTec turbocharged diesel, you can’t make comparisons to gas engines.    I know of no other engine that is harder on oil, than a BlueTec turbocharged diesel.     Mercedes published a great service bulletin in 2008, S-B-09.20/29.    That bulletin trys to explain away the most fundamental problem a BlueTec diesel stills has to this day.     The bulletin talks about oil from the crankcase being sucked into the Turbocharger.    Mercedes said it wasn’t a problem.     Well, it was & still is a problem.     Mercedes has made multiple attempts to stop the oil the turbocharger sucks out of the engine when it spools-up.    It’s this oil that clogs-up the engine’s intake system.   Mercedes has put band-aids on the problem, but they have still not fixed the problem.   If you can stop this oil going into the Turbo, you solve half of OM642 engine problems.       Mercedes has never explained why the oil gets so hot.    They’ve let Garrett, the maker of the turbocharger, explain it in an indirect manner.

So how & why does the oil get sucked into the Turbo in the first place?    Here’s the simple answer.     The Turbocharger is exhaust driven.    During DPF regeneration, hot exhaust gas is used to burn off the soot in the DPF.     If you’re driving a big heavy Sprinter in the mountains on a hot Summer day, & the DPF decides to regenerate, the exhaust gas can exceed 1600F.   That same exhaust gas is also heating the Turbo to 1600F.    As a consequence, the engine oil in the Turbo is also heating to 1600F.   (Regeneration of the DPF is what burns off the soot trapped in the Diesel Particulate Filter.    In order to burn off that soot, the engine’s computer injects extra fuel.    Not all of the fuel is burnt.   Some gets past the piston rings & into the crankcase oil.    Mercedes calls this “fuel accretion”.    That’s “fuel dilution” in plain English.   Whatever you call it, it makes a big mess inside the crankcase.   This is also why Bio Diesel is such a problem.   When Bio-Diesel mixes with the crankcase oil, you really get a mess.)

The key to understanding oil, is in the Oil’s Material Data sheet.     It tells you what the oil is really designed to do.     People often say their old car did just fine with Mobil One, & that should be fine in their diesel.     Gas engine’s don’t run extreme oil temperatures.     Gas engines don’t have exhaust driven Turbochargers with a DPF that needs to be regenerated at 1600F.    For your BlueTec diesel, low “NOACK volatility” is the most important oil spec.     It tells you how much of the oil will turn into steam when it gets hot.     It’s the hot oil vapor that is killing your engine.      If the oil you’ve chosen for your engine doesn’t publish a Material Data Sheet for their oil, forget it.    If they have a Material Data Sheet, but it doesn’t say anything about the NOACK volatility, it means the oil is at the maximum the government allows, 13.5%.      (The NOACK volatility causes pollution.   Oil companies cannot exceed a 13.5% NOACK value.    Any oil that’s at the maximum, is not a very good oil.    Mercedes does not publish a Material Data Sheet for their oil.)      Mobil One doesn’t publish the NOACK value of their ESP diesel oil.    In fact, they make that information “invisible” to the public.   “Invisible” is their word, not mine.   If you call the Mobil One help desk, they won’t tell you the NOACK value of their oil.    Send me a email, & I’ll send you a document someone sent me.   You’ll see why Mobil doesn’t want to discuss their ESP diesel oil.

Most of the problems with the BlueTec engine & its emission system are all related to each other.
If something happens, start looking for what caused the original problem.   If a sensor fails, what caused it to fail?    Often we would see a car for the first time with the Check Engine light on.    The customer just wants to fix what’s wrong, & nothing else.    They don’t want to hear any stories about maintenance, low voltage, or software updates.    When people jump around from one shop to the other, it will defiantly increase your average repair cost.    Hopefully you use the same mechanic for all your service.   He should know where you’re at with maintenance.    A good mechanic will want to make sure all of your basic maintenance is current, before he starts chasing your immediate problem.
Diesel engines have always been dirty, but the 10K & 20K service intervals have taken diesel’s to a new level of dirty.      It’s often hard to know just how slugged up the engine actually is.   You often don’t see it in the oil filter or through the oil cap.   However, if your oil filter looks like a crushed beer can, it’s time to panic.    There’s a check valve in the oil filter housing that can clog up.   Once that check valve clogs up, it starves the crankshaft for oil.
If the turbocharger fails, there are a lot more steps the mechanic needs to perform, or you will loose the entire engine in the near future.   He should follow Mercedes-Benz Service Bulletin 09.40-N-063089.    There is always more to the story.

Software updates for the engine control module, must be current.    If you have strange problems & warning lights, you will go nuts trying to figure them out.     Always update the software first.     Mercedes has updated the software for some of the BlueTec ECU’s, 23 times & counting.     Most dealers won’t do your software for updates.     They loose money doing them.     There are many problems with ECU software, & Mercedes often doesn’t tell the dealer what they fix.    One major problem with the ECU software, is it injects to much fuel for the DPF regeneration.    Another problem is the diagnostic fault codes are often wrong.    The mechanic relies on those fault codes to diagnose a problem.    The only way a dealer can know if your software is up to date, is to connect the Star Diagnostic System directly to your vehicle.    Only then, will the tester tell him if there are software updates available for the various systems in your vehicle.    All of the control modules need to be checked for updates, not just the engine ECU.
Never run Bio-diesel.    Not even B5 if you can avoid it.    When Bio-diesel washes past the piston rings, it goes into the crankcase.    Bio-diesel turns to sludge even faster.   (If your piston rings have a perfect seal, it’s harder for the fuel to wash past.)
Diesel Air Filters get plugged up very easy.    Early BlueTec’s have 2 air filters.    Later models have one.    One filter is better.    Sprinters have one air filter.    Dirty air filters send the crankcase pressure into orbit.   The more pressure in the crankcase, the more oil leaks you’ll have.   Mercedes has upgraded their air filters several times.
The Oil Separator has been updated 11 times at last count.     The Oil Separator’s job is to return hot oil vapor back into the crankcase.   When you see oil leaking out of the front of the turbocharger, it came from the Oil Separator.   This is called the PCV valve on American engines.
The plastic Air Intake at the Turbocharger also melts from the extreme heat.    The hot oil vapor that was “normally” going into the Turbocharger; instead leaks onto the Swirl Motor & shorts it out.    That causes the engine to go into the Limp Home mode.     Oil then drips out the drain holes in the block & all over your driveway.     If you’re really lucky, the engine ECU will see “Low Boost Pressure”, & turn on the check engine light.   If any of the oil soaked air intake seals are out of place, you will get “Low Boost” fault codes.
Mercedes admits to Timing Chain failures on all 2008 to 2015 OM642 Diesels.   Zinc in motor oil helps prevent the Timing Chain from failing.   (1400 to 2000 ppm of zinc is a good number.)   “Low SAP’s” diesel oil has 900 ppm.
As of 2016, almost all of the important parts on this engine have been updated by Mercedes to solve some sort of emission or oil leak problem.    Almost any problem the BlueTec has, is a result of the same core design problems that bedevils every BlueTec made.   It’s likely you’ll need to replace many of these parts at some point.    Starting with model year 2014, Mercedes started using a 13.5 quart oil pan.   Those engines are much better than the older 8.5 quart oil pan.
People are always asking if I think they should buy a new BlueTec.   Yes, if you do the Break-in, & follow a simple maintenance routine.    The new engines will be very dependable.    A new BlueTec Sprinter is a darn nice vehicle.

Depending on where you live, you can have completely different issues.     If you live where it’s often below freezing & make short trips, there are 0w/40 oils with very good NOACK volatility.
Much lower than the official Mercedes-Benz oil.      In subzero weather, change the oil every 3000 miles.     Cold weather is harder on the oil.    In the summer, use a 10w/60 or 20w/50 diesel oil.   There are so called “experts”, that say you should never use a 50 or 60 weight oil.   They say these oils are to thick for modern engines with tighter tolerances.    These new diesels run so hot, & have such high fuel dilution, they have to have high viscosity oils.   It appears Mercedes-Benz finally agrees.   These 20W/50 & 10W/60 oils are now approved in the 2018 Sprinter Owners Booklet.
On a new vehicle, run DPF fuel cleaner in every fourth or fifth tank of fuel.   BG 245 is a excellent fuel system cleaner.
Keep the AdBlue tank close to full.  In subzero weather, you don’t want to risk it splitting the tank.  Use a name brand AdBlue.   Mercedes has also admitted to a 100% failure rate on all the 2009 to 2015 AdBlue tanks.
Put 2 bottles of engine oil flush in your dirty oil right before you drive in for a oil change.   It will help break up the sludge.   Liqui Moly or Amsoil Engine Flush are both very good.    However, you can use other brands with no problem.     Do it on every oil change.   Mercedes & practically every oil company says you shouldn’t put any additives in the oil.   Generally, I would agree.   But there are additives that have been very effective at fighting sludge in the crankcase.
Get a super magnet drain plug from Dimple Magnetic Drain Plugs.   It will trap all the metal smaller than 35 microns the oil filter can’t stop.
Take the Belly panels off under the engine.    It needs all the air flow it can get.    There really is no other way to get rid of the crazy heat.
If you ever compared the oil filter from a 1980 diesel & a modern diesel, you would notice the older oil filters were twice as big.   Bigger is better.   Diesel oil picks up a lot of soot.   That’s why it turns black so fast.   Soot in oil is bad.   Change the oil filter every 2500 miles.
Only the BlueTec diesel engine has Motor Mount support arms that are filled with a special grey “heat sink” material.    (Sprinter’s don’t use this system.)    They were designed to withstand extremely high heat.   Engineers are trying to prevent the extreme engine heat from melting the motor mounts.     The BlueTec engine runs so hot, it melts the grey “heat sink” material that was designed to withstand extreme heat.    Grey sludge leaks out under the engine & causes a mess you won’t believe.   If the engine runs so hot it can melt this stuff, guess what it’s doing to the oil?    (“Engineered like no other car in the world.”)
Change the Air Filters every 20000 miles.
Fuel filter every 30000 miles.    Replace the rubber hoses to the filter.   Rubber flakes off old hoses & ruins the fuel pump.
I’ve heard that Bio-diesel is unintentionally getting mixed up at stations by careless fuel delivery drivers.    Some stations don’t label the pump.   B5 is the only Bio Diesel Mercedes says you can use.   Don’t touch the stuff.   Refuel at busy stations.   When traveling, plan ahead & refuel with a half a tank with non Bio Diesel.   That way if you can’t find the right fuel, you can keep going until you do.   I have a national list of known diesel stations that sell regular diesel fuel.
Mercedes has now started to recommend the EGR valve be cleaned every 40000 miles.   Burnt oil clogs it.   
If you do a lot of driving in heavy traffic, ask the shop to do a manual regeneration of the DPF the next time you’re in for service.    The Mercedes-Benz tester can force the system to clean itself.
Drive it like you stole it.   Kick it into passing gear when you’re going up a long hill.    Sensors in the DPF tell the ECU when to much soot has increased the back pressure in the DPF.    The more you “blow out” the DPF with hard acceleration, the fewer times the ECU will ask for regeneration of the DPF.    That means you’re not going to get all the extra fuel dumped into the crankcase oil when the ECU regenerates the DPF.    This is why owners who drive their diesel hard, actually have fewer problems.    It’s not a myth.     (This is also in the 2018 Sprinter BlueTec owners manual.)
Never let the engine idle for long periods.   It kills the turbo.   Sprinter offers a “high idle” option, but I still wouldn’t let it idle.
Some states only sell Bio-diesel.   If you live in those states, change the oil every 3000 miles, with a high quality diesel oil.

I’m getting some reports of Sprinter frames cracking at the rear suspension.   I’m not sure what this is about, but it seems to be in areas that use salt on the roads.
Dealers are telling owners the vehicle can’t be fixed & Mercedes won’t pay for it.    Some dealers have dozens of cracked Sprinters setting on the back lots.    I don’t know what years or if they were used for towing.    It’s worth asking your local mechanic to check for stress cracks in the rear, near the sway bar & shocks.
There is a whole lot more than this, but I have to stop someplace.
November 2018