i just broke in a 292 i rebuilt, i got some great advice here. i used shell rotella 15w 40 and gm eos- i had to get it from dealership but you might be able to find it elsewhere. i switched over to a synthetic blend after 500 miles on my last engine i did before this one. you don't have to but i've heard you shouldn't break it in with syn so rings seal. my breakin went great. i am glad i used the shell.
