On a fresh built 331 stroker. Do I need to use a break in oil? If not what weight? How should I do break in procedure?

 

10w 30 will be fine, I often use quaker state for such, to each his own.

 

10-30 Castrol warm up engine and make proper adjustments. Now make 10 20-60 mphr acellerations at wot. Let engine go back down to 20 mphr on zero throttle. After this flog the bitch as you see fit. Oh, almost forgot change oil and filte rafter the 10 cycle. Bubba

 

how bout sae 10w30 castrol gtx? What is wot?

 

will work fine^^^^^wot = wide open throttle

 

10w 30 is fine. be sure you beat the hell out of the motor to break it in

 

My engine builder recomends using break-in oil with zinc in it. From what I understand the zinc coats the bearings and other parts and helps with longevity.

 

5w20 is what I use. You need an oil that's as thin as you can get it on cold starts so it has a higher viscosity to start with. The thinker the oil, the worse it is.