Hope it is okay to revive an old thread. I was looking for information on break-in oils and found this thread. I just had an engine built and the vendor recommended an elaborate break-in procedure and told to use break in oil. They said to change the oil at 50 miles, 150, 250, 500 and finally at 1000 miles to the standard oil. The shop is going to put in Motul 0w40 break in oil. I never used a break-in oil so I figured I would research it. And I found a thread on a Vette forum about break-in oils by someone that at least seemed to know what he was talking about. He said he is an engineer and has a blog listing characterists of 170 different oils if I recall. Anyway, at least according to him, doesn’t matter what kind of engine you have, tappet or no, do not use break in oils.
Break in oils, in theory, have low anti-wear additives to allow for quick ring sealing. But, high zinc to prevent wear on the rest of the engine. According to him, you just can’t have one oil that allows wear on some things and not on other things. Further, he says that zinc, just by itself, tells you nothing about an oil’s anti-wear characteristics and so even if break-in oils have a lot of zinc, they still stink at anti-wear. And of critical importance, he says that rings don’t actually get seated any better or any faster with break-in oils. Thus, you are just harming your engine using break-in oils.
Again, this is not me speaking, I’m not an engineer so I don’t really know. But, I can say that it seems to make sense to me. High performance engines come out of factories all the time and don’t need no stinkin’ break-in oil. Since my shop is going to install Motul 5w40 break-in oil, I think I will follow their procedure for the first 50 miles. And I will do the oil changes at their recommended intervals even though that is probably more than really necessary. But, I don’t want to do fewer changes than recommended so I will do it.
The author suggested using oil on the thin side, like 5w-30. I happen to have about 4 gallons of Amsoil 5w-30 in my garage, so I will use that for my “break-in” oil for the oil changes at 50, 150, 250 and 500 miles.
I don’t know if you can link to other forums here. So I didn’t put a link. Search for “Test data on 9 different break-in oils”
