Do you have flat tappet lifters? Then this stuff is WRONG! This is a break in for Roller Lifters.
You think break in additive is expensive? Wait till you pay for PROPER oil for flat tappet cams...
Only 2 I know of are Amsoil full synthetic 10w 40 with Zinc and Phosphorus and Joe Gibbs racing oil.
Other then that there is no oil left on shelf at auto parts stores for flat tappet cams. Also the additives at parts stores for Zinc and Phosphorous are a help, but still for roller cam engines and not enough for adequate protection of flat tappet cams.
If more people realized this. these old engines would last longer...