Thoughts on oil type for breakin?

[Indawoods]

I have read a lot of articles on breaking in a motor and there are varying views on the type of oil to use.
Some say never use synthetic oil for initial break-in.
Some say use what you are going to run.

Anybody have any thoughts on this?

I have always used a castor based oil for break in and then run synthetic.

[fuzzy]

I agree......Not to break-in w/ synthetic. I think the 'run what you run' comment stems from pre-synthetic times. Regardless, it makes since to me. Synthetic's virtually stop wear, and won't allow an engine to break-in correctly. I've always done the same...Bean Oil for a tank, then back to syn...

[IdahoCharley]

I use to be of the opinion that you should not use synthetics for break-in then I started to use them. At my yearly rebuilds my piston, piston blow-by, end-ring gap and side ring clearances could not look better IMO. I'll try to figure out how to post pictures tomorrow and show a piston from last year with about 1300 miles on it.