What kind of break-in oil to use?

In the next week or two I'll be looking to fire up my rebuilt 383 (hydraulic flat tappet) . What break-in oil, or additive, and weight do you prefer?

I like Penn1 30 Break in oil. Old name Brad Penn.
Spoke with tech just the other day about the high zinc and was told it's the same oil and has not been changed.
Bob.

Penn, Lucas, Gibbs...all good.
I'm sure you know the procedure.

GM E.O.S. is what I used years ago.

Valvoline VR10x30 with a bottle of zinc additive

Thanks guys.

Van

Last 2 solid cam engines I built were broken in with Gibbs break in oil and are both still going strong 10 years later

Gus

What make cam? At least one cam maker sells their own labeled break in additive.

I've used Joe Gibbs Driven break-in oil in the most recent flat tappet motors I've built and haven't had any issues. No need for any additive.
About 4 years ago I used Valvoline VR1 race oil w/ Comp Cams break-in additive on a 440 hyd. flat tappet build. No problems w/ that one either.

These were all fairly mild hydraulic flat tappet cam street engines. Anything aggressive, I prefer a roller.

Cam builder's break-in lube on all rubbing surfaces and Valvoline VR1 10-30 (for my clearances) and no problems here either.

Joe

For every brand of break in oil and additive that’s available........ it’s someones favorite.

My favorite is the Driven “BR”, which is 15/50.