Originally Posted by Otto Skorzeny
I think that is higher than most oils but not quite the optimal amount as researched by the Classic Car Club of America. They produce their own brand of oil with 1600ppm ZDDP.

I've been using T4 for years but was recently told that they had reduced the amount of zinc in it. I believe it used to be around 1400ppm but I don't remember now. I'm glad to know you got the straight dope from the manufacturer.

Here is a link to purchase Classic Car Motor Oil and read more about ZDDP in oil if you wish.

https://inrccca.org/product/classic-car-motor-oil/

I’ll have to give the CCCoA a try.


Update from shell below after asking if that value is consistent across the weights if oil in the T4 line:

“ Hi,

Thank you for contacting Shell Technical.

You are correct except for two products, Shell Rotella T5 Ultra 10W-30 and Shell Rotella T6 Multi-Vehicle 5W-30.

Hope this helps.”

Last edited by Rust; 10/21/2022 5:53 PM.
1955 Chevrolet 3800 2nd Series