So I live in hot as ***** South Texas and I took in my FB for a change of fluids (Tranny/rearend/motor) I had the guy put in syn oils in both the tranny and rear end but for some reason he put 5w20 into the motor..

Will 5w20 hurt my N/A A12?

What motor oil do you guys think is best for ball soup hot south Texas?
I was thinking to run 5w30 and in the past i ran just 10w30.

 

First off, some semantics: it's a 12a engine not an a12.

Second, going off FC/13b requirements, 20W is too thin for summer use. I'd say 10W-30 at the minimum.

https://www.rx7club.com/2nd-generati...7/#post5131205

Edit:

Here you go. This is a 1st-gen specific link: http://www.rotaryheads.com/PDF/1st_g...aintenance.pdf

Suggested weights:

Under 0º F: 5W-30

Above 0º F: 10W-30

And you'll find a thread in the 1st gen FAQ where most people say they use 10W-40 or 20W50.