Interesting.
I'd call Lycoming on that before I'd let anybody try synthetic oil in my new
cylinder. It's my understanding that the reason straight mineral oil is
used for break in is that it does not contain detergents, adjuvant, or
anti-wear agents. Mineral oil will allow the proper amount of heat,
friction, and pressure to develop in the cylinder necessary to allow your
rings to set properly, without suspending particles and forcing them back
through your new cylinder. Unless somebody has developed a special
synthetic oil designed for break-ins, I would think that a synthetic oil
would contain these undesirable agents. I would also suspect a synthetic as
well as being "too slippery" or capable of removing too much heat,
preventing the rings from setting properly.

What brand/type of oil is your A&P recommending? Any supporting info from
the manufacturer? Lycoming?

Jim


"Robert M. Gary" wrote in message
oups.com...
On Aug 31, 11:02 am, "Jim Burns" wrote:
http://www.lycoming.textron.com/cgi-...=break+in+proc...

A new nitride cylinder will break in fast. Keep your power high, don't
baby
it. Straight mineral oil.

Now the A&P is saying that mineral oil is out-dated and that modern
synth oils are better for break in than mineral oil.