I remember hearing someone explain that much of the design of the PRV engine was from an 8 cylinder diesel engine. They said that this contributed to the durability of the engine. Anyway, if this is true then it could make sense that it would be specified to use an oil more suited to a diesel engine. But then I've heard a lot of things about DeLoreans from door opening motors to helicopter engines. Can anyone substantiate the diesel engine story? Walt Tampa, FL