Engine break in oil?

That’s the thing right there that I do with the oil.
Tighter clearances for longevity street engine expected to be in service for a long time. Decades expected.
Looser for the street strip rides.

As time goes on, after many many miles, they’ll start to require a thicker heavier grade.
So true, I will put stuff together, and I only want to do it once.
Its a lot more fun to wash and wax a car on Sunday, than laying under it fixing something.