OM60x engines have been developing "O" ring leaks since the introduction of low sulfur diesel (LSD 0.05%) in the early '90s. Seems to me that about 1-2% developed leaks every year. Never figured out why some did and some didn't (I've owned 7 different OM60x engines). The OM61x engines seemed almost immune to those leaks. As my cars age however, I've noticed that the fuel lines are deteriorating and starting to seep/leak. ALL of my cars date from '84-'87 and old to new, every one has had at least ONE fuel line start to seep. Based on past experience, that's just the effect of age - my cars are all about 20 years old and most of the lines ARE original. None of my cars have experienced ULSD. All have used LSD for more than a decade and several of them have had tanks of run B20 run thru them. That has changed NOTHING. With higher concentrations of Bio, older fuel lines and seals may deteriorate RAPIDLY.

I expect that there will be some number of failures with ULSD, but that's largely a matter of how much the old seals have swelled. When the ULSD is used, the "O" rings and seals try to return to their original size, but if they are seriously distorted, they will not be able to seal as they shrink and will leak. That's NOT really the fault of the ULSD but of the fuel that was used previously (and it's sulfur or additive content) causing the seals to swell and the aged seals no longer being pliable enough to seal as they shrink.

Marshall