I would have to agree about not painting. I haven't used it on an automotive engine for some period. I don't think it will help
oil flow any better than deburring and polishing in the same area. That's what I have done for quite a while. I have always been worried about the possibility of paint flaking off and destroying an expensive piece. Although, I have never seen any indication of that, it is always a possible. Since most blocks have casting "slag" that is left, by removing that and a little time with a sanding drum accomplishes that same without an potential side effects. I wouldn't have used it on the Harley if I wasn't trying to stop seepage through the early castings.