The normal rule or as I was taught many moons ago, is to run the mineral oil until the oil consumption has stabilized. The mineral oil does not have the lubricity that AD oil has and I like to replace it soon after the engine is broken in. With 5 hours on the engine the cylinders should be broken in by now. Easy way to check is to pull the bottom plugs and check for oil wetness. There are many who don't agree with the use of mineral oil as they say AD oil will work just fine. I have never wanted to chance it for the fear of glazing the cylinders and having to pull the cylinders and starting all over again at my expense. The first oil change after a major is a good time to verify the ignition timing and idle mixture as well as a good visual inspection. Glad to hear that all is progressing nicely...

Thanks Don and Tom,
I am almost finished with my restoration and have about five hours on the engine. When I hit ten hours I am going to change the oil and filter and switch to AD oil. I appreciate the input.
Reece

Don,
I talked to Superior Airparts and they sent me their recommended break in procedures. They say it usually takes between 10 and 15 hours to fully break in a new cylinder assembly and recommend mineral oil for the first 25 hours so it sounds as if you were right on target. Thanks.
Reece

Ronald,
I had read this article previously. My new engine now has 10 hours on it and oil consumption has slackened dramatically but it is still blowing and burning some. Superior recommends mineral oil and so does Continental so I will just stick with their literature and take the safe road. The engine is running strong with good oil pressure and temps both.

I'm sure AD oil would be great but there just might be some reason the manufacturers make this recommendation so I'll err on the side of caution and do what the FAR's advise.....follow the manufacturers instructions and specifications. Thanks!
Reece