400 break in?

[jdsdidit]

I've got my rebuilt 400 ready to drop in and am wondering which oil to use during the break-in period. Is it Ok to use a diesel oil for break-in or should I use gasoline engine oil for break-in and then switch?

Thanks

[jim henderson]

READ the posting on Cam breakin in this same forum. It talks in more detail about what I say below.


Many of the guys and several cam manufacturers are recommending diesel rated oils for new engines especially if you used flat tappet lifters, I. E. NOT Rollers.

The reason is that for smog purposes, the latest auto rated oils are barely adequate in some of the antiscuff additives. Without the additives, you run a risk of wearing out the cam and lifters. The diesel rated oils still have good antiscuff additive pacakages and work better for new engine break in. Also I think they recommend diesel for continued use if you have the flat tappets I mentioned.

I even think the same recommendation held with synthetics since the auto rated syns also have low additive packages.

Good Luck,

Jim Henderson