Since finances are tight right now I've put a hold on rebuilding the old 454. If you've kept up with my prior post you know what my issues are with my 1973 Chevy c20 454. If not then the 454 is basically tired, kinda runs like I'm pulling a big A-S boat anchor, lol. On YouTube there are many videos on oil additives and Engine Restore seems to be the most popular but there are a few on Marvel Mystery Oil. I grew up watching my grandfather use both products in tractors, old trucks and boats but the crazy moonshine drinking, pipe smoking, dancing around in his baggy briefs old fart has since passed away so I never got his expert advise on which was better. No joke, he used to dance around in front of my friends in his baggy briefs, cool old okie but anyways looking online and averaging out the oil additive articles it's about a 50/50 tie between the two. Here's the big question, I'm wondering what would happen if I used both at the same time? Substitute a couple quarts of regular engine oil with a quart each of Marvels and Restore? Didn't mean to talk your ears off but has anyone tried this epic idea?