I'm doing an article on basic British Car maintenance for Sports Car Market
magazine and also, incidentally, rebuilding the engine on my MGA, so the topic
of oil is very important to me.
Here's what I understand is the conventional wisdom:
Nearly all oils for gas engines have reduced or removed the additive zinc
dithiophosphate (ZDDP) from their oil because of negative effects on catalytic
converters in order to meet new American Petroleum Institute (API) standards.
However, this additive was essential to long-term survival of tappets and cams,
i.e. in all vintage British engines.
Having researched most oils on the market, the conclusion is that only two
oils still on the market still have this additive, Castrol 20W50 GTX and
Redline
10W30 or 10W40. Castrol HD30 still has the additive, so would be appropriate
for the first 3000 miles on rebuilt engines, though because of the
high-detergent nature, would NOT be appropriate for gearboxes.
I know this topic has been bandied about on this list, so for you technical
folks out there, is this the latest word? Are there any other oils that might
still have ZDDP (e.g. I've heard that Valvoline Racing oil might), Are there
other oils, such as Amsoil, that don't have to meet API standards and so might
still be usable in our engines?
Thanks for your input.
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