Hi Gary, Assuming new rings and at least newly honed cylinders (if not new cylinders), then:
Engine should have straight mineral oil for the first 10hrs. Ignition OFF Pull one plug from each cylinder. Spin by hand, (will pump oil thought engine) Replace plugs and run? Worst part is its pretty important to run at more than 75% power for the first ~1-4 hours. (Not entirely compatible with testing out a new plane too! But the high power (and temp) is important in seating the rings. If you baby it, the rings may never seat.) Watch for oil consumption to drop and cylinder head temps to drop - then you?ll know the rings are seated. I?d replace the mineral oil at 5 and 10 hours, and replace with something like Aeroshell 100. The which oil conversation seems one of the strongest breezes flapping aviation gums out there. I?m no expert, but I have read that most oils start breaking down very close to ~450F. Seems like everything goes to hell about there. High temps around the exhaust valve stems cause a lot of problems, compound by oil breakdown. I?m a sucker for technical mumbo-jumbo marketing info and some time ago Castrol Aviator 100AD used to market their oils as having a higher breakdown temp than Aeroshell. I have no idea, but I tend to get the Castrol when I can find it. Cheers, Owen
