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Any high quality oil will work, 10W-30 or 10W-40 depending on the low temperature it will be started in. The important thing is to find an oil with zinc additive or add the zinc separately if you are running flat tappet lifters/cam. Current oils don't have the additives needed for old cars.
 

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Any high quality oil will work, 10W-30 or 10W-40 depending on the low temperature it will be started in. The important thing is to find an oil with zinc additive or add the zinc separately if you are running flat tappet lifters/cam. Current oils don't have the additives needed for old cars.
I thought the zinc additives were needed for break in period. And not necessary for the rest of its life. Definitely nothing wrong using it forever. I did it for 3 oil changes, on new engine, and haven’t used it since. 10W-40.
 

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I thought the zinc additives were needed for break in period. And not necessary for the rest of its life. Definitely nothing wrong using it forever. I did it for 3 oil changes, on new engine, and haven’t used it since. 10W-40.
Yes, needed for break in, but if you have a flat tappet cam (hydraulic or mechanical) modern oils do not have enough zinc (as ZDDP) to prevent premature wear. You will need an additive or a racing oil. Shell Rotella diesel motor oil also reportely has more zinc additive than motor oils for gasoline engines. If you rebuilt your motor with a roller cam any of the modern oils should be fine.
 

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Discussion Starter · #7 ·
I found Castrol GTX classic (high zinc content) 20w/50w at Walmart. This is perfect for our hot weather here in the south.
 
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