Does anyone know what oils are recommended by the likes of Cummins, Cat, Detroit Diesel, MAN, MTU, et al engines (as in big and slow turning) up to say 19 liters? I think the intervals run about 400-600 hours unless the old oil is burned in combustion and continually replaced (I can't remember who does that) and was wondering if synth like Rotella is indicated like it would be in road-going versions of the engines. And at what weight? Or, have the marine engine makers stayed old school with mineral because, hey, it works and always has?