My dealer mentioned this was going to happen and sure enough, all fuel stations now are selling 5-20% bio diesel (in Minnesota). Dealer said the bluetec engine is designed to run well with 5-10% bio, but above that mercedes will not warranty/stand behind any fuel related issues. He recommended changing fuel filters more often as they can get clogged more easily with higher rates of bio diesel.
I have since found 3 local fuel stations that sell premium diesel, which is not blended with bio. It cost more, but our bluetec seems to run smoother when using premium.

Anyone know more about using high percentage of bio and it's long term effect?

 

/suspiciouseyeballs

 

The problem is not the bio itself (at least not for the fuel filters) but rather switching from 0% bio to a bio blend.

100% diesel will leave very minor sediments and films in the fuel system over time. This is totally normal and MB over-designs the fuel system with this in mind.

The problem occurs when a bio blend is introduced because the bio is a stronger solvent and will loosen those normal deposits and this is what causes problems in the fuel filter. Since you have probably been using 5% bio the entire time in MN your fuel system is probably pretty "clean" and 10% (or even 20%) is not a huge concern going forward but changing the fuel filters sooner is not a bad precaution. The concern is for vehicles that have been running diesel for years that switch to a bio blend. MN recently increased from 5% to 10% for summer months (link) and will return to 5% during winter. At some point MN is supposed to increase to 20% but the date keeps getting pushed back.

What is a potential concern is your OIL system. The bio has higher lubricity (normally a good thing) but this can cause some fuel to squeak into the the oil system over time. This is particularly an issue during the DPF regen cycle when fuel is sprayed directly into a cylinder during the exhaust stroke. The diesel will vaporize but bio droplets have the theoretical potential to stick to the wall and seep into the oil during the completion of the stroke.

Over long periods of time fuel in the oil system will dilute and degrade the performance of the oil ---and with enough heat and time--- create the dreaded sludge. This is why when 20% was introduced in Illinois MB put out a brochure telling folks they could use the bio blend but oil levels should be monitored for increases as this would be the first symptom of fuel in the oil system. Fortunately, it has not been huge problem in IL yet (knock on wood).

Thus, the simplest and easiest way to deal with the issue is to change the fuel filter at 20K (instead of 40K) and do more frequent oil changes. There are entire fleets of Sprinter vans out there with a detuned version of the same OM642 motor that are running 100% bio without problems. The fleets are simply doing more frequent oil changes as a precaution and all is well.

There is also some good news. Bio has a higher Cetane number (http://en.wikipedia.org/wiki/Cetane_number) than the #2 diesel typically found in the US, which is unfortunately much lower than Europe, so the engine itself will run very nicely (smoother/quieter) on B5-B20.

Cheers!

ps As a fellow Minnesotan how did you find the stations without bio?

 

I live in Florida and use BP diesel only. How do I know if it is a blend or not?

 

^^great explanation! Thanks....I feel a bit more at ease now...

 

Typically not an issue in states that don't mandate bio as bio is more expensive and fuel suppliers have no incentive to raise their expenses needlessly.

In states like MN and IL it is a political football and essentially an artificial price support for the benefit of soybean interests that have suffered from the reduction in consumption of hydrogenated oils.

 

Best explanation I've read on bio diesel. Thanks for taking the time to spell it out for us.

 

Ah, that is what I though. Just what we need is more government in our lives. The alcohol in the gas is bad enough and they want to increase it to 15%. I remember shortly after they started using alcohol, the EPA came out and said that the damage to the environment to grow the corn greatly negated its use as a oil saver. Funny how they changed their minds to keep some states/politicians in the alcohol business.

November is very important

 

Well... political aspect of biodiesel is daunting because frankly the impact is non-green ... subsidies make higher bio-content as affordable or more affordable than 5% - and unfortunately as a fuel - higher content bio-diesel is less efficient, and frankly less controlled from a content/quality standard, and in the case of Illinois retail pump labeling and call out poor.

Euro passenger vehicle diesel engines as developed over past decade of development have become more efficient (higher output), quieter, and smoother than ever before.

In Euro passenger vehicle diesels post-07 (approx) almost all have a "initial-combustion" process whereby a small amount of fuel is micro-injected into the cylinder, then that micro-injection is "sets-off" the main injection into the cylinder - leading to hotter/bigger/more-efficient "big bang".. bang-to-Bang.

Higher content bio diesel - think less efficient fuel - isn't as effective in the micro bang..

Trnsport/truck disels - by and large - have become more efficient - but most at this moment still run a standard diesel combustion process.

So - for passenger diesels - higher bio-content diesels fuel wise goes a bit backward - for transport diesels higher bio-content diesels is a bit less efficient but doesn't run contrary to the ignition tech there.

That's my dime's worht of take on the situation - it is hoped MN learned somewhat from the boon dongle from Illinios.

Keep the beat !

 

Several stations in Missouri, too.