Originally Posted By: m37charlie
Exactly my point. they do different things. It is fallacious to try to rank oils for different applications. Low SAPS oils, diesel oils, and an oil optimized for European high performance engines can't be ranked against each other. Personally, I woulld not use them interchangeably in the same engine. As my sig points out I have 4 oil applications in 5 vehicles and I don't even think about trying to find one oil that will work best in all.
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Why use an oil designed for American larger diesel engines when there's an oil the mfg specifically approves (not knowing the 50x #, I don't know which one, but M1 0W40 meets a lot of them)?
Modern high-performance diesel engines are not that different from one another, no matter where they are designed or assembled.
VWoA tried to tell us with the 2004 MY TDIs that a special oil was required to protect the cams and lifters. But many owners who used oil that met that spec still had problems; then owners who switched to an API-rated oil like Delvac 1 and M1 TDT reported years of trouble-free driving. Now those CJ-4 rated oils have been reformulated to meet the demands of modern emissions systems. So the same diesel-rated oils used by pickups and heavy-duty trucks can work very well in high-revving German passenger cars.
Volkswagen TDI engines need the same kind of soot control, and the same kind of detergent and anti-wear additives, as Cummins and PowerStroke engines. And an entirely different kind of technology from the requirements of turbocharged gas engines.