Synthetic Oil Improvement in /6

1970Duster said

Zddp is for the flat tappet cam. The oil out today lacks the higher levels of zinc in it because it messes up the cat in new cars. Understand full syn (maybe blend as well but I'm 100% on that) will find the smallest leak and start leaking a lot because syn is a lot finer than regular oil. Now don't get me wrong all of my cars run full syn Mobil-1, just letting you know.

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I wondered why they quit using zinc.
That makes sense now.
I don't know what to even run in my slant 6, just got it, so I didn't buy any oil yet.
And eventually this winter, putting in a 440. I am lost with oil anymore for our older engines.
Funny you brought up the leak thing!
My wife had a Nissan Xterra. I really took good care of that truck. Changed oil always on time. I switched to synthetic at about 90K. And it started having small oil leaks in a short period of time. Thought it was my imagination!...#-o