of early 3.0L engine (US 1986-1987) had been corrected. However, in the 3.5L there exists a different situation that appeared on some engines; eventual head gasket erosion, and thus passage of oil into the #1 cylinder. As the 3.0L engine uses the same head oil passage design, yet does not appear to exhibit the problem - it might be that the larger bore in the 3.5 engine, the higher pressures, and resulting smaller head gasket surface area could conspire to cause a gasket erosion issue. Versions of OM603 Mercedes 6-cylinder diesel engine OM603 Diesel engines by model Straight-six engines