Dennis Kirban has been going on and on about the oil additive ZDPP something or other for a while now. It sounds like a good idea, but I don't feel like paying $50 for six bottles of this stuff and having to complete a waiver for "off highway use". A friend of mine uses the Rotella diesel oil, and he hasn't had a problem. Kirban says you should use it because of all the detergents in the diesel oil. Auyone have any info on this subject?