I believe California regs encourage biodiesel concentrations of up to 20 percent. I have a (former) CA car and its oil was the consistency of runny pudding for the first couple of oil changes.

 

For trucks yes and CA trucks stops offer only B20 from what I noticed. Still D2 sold at other stations is not allowed more than 5%.
I hear new MB diesels allow for B20, but that is future.
Strange as my 2017 Ford Powerstroke allowed B20 and I actually had good results with it. Ford is not hassling customers with special oils, like MB does, but then the 6.7l offer 62HP/l, when MB is reaching 100 HP/l

 

While federal regulations call for a minimum of B5, almost half of the continental US states have local mandates in place that result in stations pumping out up to B20. Just as an example... Minnesota (https://www.mda.state.mn.us/environm...sota-biodiesel) - No. 2 diesel must be blended with at least 5% biodiesel from October 1 to March 31, 10% biodiesel from April 1 to April 14 and 20% biodiesel from April 15 to September 30; Massachusetts (https://www.mass.gov/service-details/advanced-biofuels) - Bulletin 13, issued in 2006, directs all agencies of the Commonwealth to use a minimum of 5% biodiesel in both on-road and off-road diesel engines, beginning in 2008, and use a minimum of 15% biodiesel in both on-road and off-road diesel engines, by 2010. Other states have similar mandates... TX, CA, IL, IN, IA, MN, MO, ND, OR, WA, NY, OH, PA, LA, AR all have state-level mandates that stipulate biodiesel content up to B20. See https://afdc.energy.gov/fuels/laws/BIOD if you want to see the various biodiesel content mandates by state.

As for the MB 229.52 oil spec, the first article that came up on Lubrizol was https://360.lubrizol.com/2020/Unders...-Specification. There are others that go into more detail. Google "MB 229.52 oxidation stability" and "MB 229.52 biodiesel"... the top hits are from various oil manufacturers that mention biodiesel compatibility, but it all boils down to oxidation stability. When you Google "biodiesel oxidation", all the hits that you get are about how biodiesel is more prone to oxidation - and the very first hit that you get states "Oxidation of biodiesel leads to the formation of hydroperoxides, which can attack elastomers or polymerize to form insoluble gums. Oxidation products such as hydroperoxides and carboxylic acids can act as plasticizers of elastomers."

Once you take into account the US biodiesel content, oils unable to deal with the resulting amount of oxidation and long OCIs, you have a recipe for disaster and the reason for all the seized / blown OM642s where the oil has gelled up.

 

Still amazing why OM642 engine seems to be only diesel subject to the phenomena.
From dozens of other diesels who are allowed to run on B20.
Once again, any fuel with more than 5% of bio, can no longer be sold as D2. It has to be clearly marked as biofuel.

 

Sounds interesting. Will say though however the T6 does run and meets specs of diesels with SCR/DEF systems which is on all modern diesels in US (post 2015 at minimum) and does just fine. Regardless of the name adblue is a SCR system that injects DEF same as the others.

Now the biodiesel thing I know requires increased OCIs if you are running over the required manufacturers "limit". I believe in the Cummins its anything over 5% bio (could be 20% been a while since I cared to look) and I dont recall what the new OCI is maybe half of what usual recommendation is. They recommend increased oil level checks as well.

Wanted to add I wonder if the crappy listing of biodiesel content in the US has anything to do with the issues on a engine that apparently is extremely sensitive to it.

 

Every single OM642 engine that has sludged up and has been taken to a dealer had an oil sample taken out and sent for analysis. All of them have shown significant diesel contamination of the oil.

As for failures in other cars, I have only ever seen this happen in DPF-equipped vehicles that have had repeated failed regen cycles and where the oil and filter were not regularly changed (at 50% of the original OCI if the fuel contained more than B5) or that had another issue like overfuelling. There have been numerous reports of the oil gelling up in VW TDIs for example, and in all cases that I can remember where they did a UOA it was due to diesel in the sump.