Proper Break in Procedure
 

I just finished a rebuild of my 1973.5 911 T Targa. It has 83k miles on its numbers matching engine. What started as a re-seal resulted in new bearings, timing chains, valve guides and new intake valves, new rings, oil pump upgrade, new rubber hoses. Still has original 2.4 pistons. I filled it with Brad Penn 30w Break in oil. It is running fine. How should I break it in? At what point should I change to my usual Brad Penn semi-synthetic 20W-50? I am careful not to lug the engine, but once warmed up how high can I rev?

Thank you

when ever I do a rebuild, I drive the car or ride the bike in normal city traffic and change the oil and filter after the first 100 miles. After that I'll change the oil and filter in the 700 to 800 mile range, and then I go to my normal 5000 mile interval

I break it in with a generic oil and after that I may go with synthetic but the issue of using synthetic on a street bike or car as having any real world advantage is still up in the air with me.

more often than not, I go to Autozone and grab a jug of their oil for my Suburban and my 944 (now sold)

my Jetta TDI, I use a VW spec 507 oil, my Kawasaki Concourse has a wet clutch so I use something with JASO MA, my airhead has a dry clutch so I use whatever I feel like at the time

What ever oil you choose...do NOT add any friction reducing modifiers to it for break-in!
You want the tiny bit of wear to happen so that the rings and valves seat correctly.
If you use reduced friction oil (like synthetic) or additives...you defeat the break-in....or lengthen the time it takes to break-in the engine.
Bob