What about zinc?

RustyRatRod said

Not anymore. The ZDDP was reduced a few years ago. About the same time converters were required on diesels, I believe. About 2004.

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Yes, but they still have some stronger detergents and other chemicals that are just better than the car oil ones. That is why I used the lucas stabilizer with it. Zinc is really just an extra lubricant, so I just I used the lucas as the lubricant instead.
That is also why I said if he is uncomfortable with that, zinc additive will never hurt.