This is the only attempt at scientific testing in air cooled engines that I know of. He didn't like the piston scuffing with 100:1
http://www.geistware.com/rcmodeling/articles/oil_test/index.htm
In the case of Amsoil 100:1 mixed at 100:1, there is so little oil in the mix, the combustion of the oil added very little to the energy needed to turn the prop. The HS needle had to be opened to allow in the extra required gas to turn the prop at full speed. The presence of carbon with this mix indicates that the oil was burning but was in insufficient quantities to provide much power.
Finally, please remember that this test looked at carbon formation but did not examine the ability of the oil mixes to lubricate.
Several individuals have ask me to conclude which oil I would use in my "high engine stress" flying in the summer of '05. Remember, this is my biased opinion.
1) I would never use Amsoil 100:1 mixed at 100:1. There is no decrease of carbon formation and I noticed an increase of piston scuffing on the test engine. Even though I have over $20,000 of engines in my shop which I did not purchase on my own money, I still think it is "nuts" to shorten the life of an expensive engine from limited lubrication for the benefit of airplane cleanup.
2) If you don't mind scraping a little carbon every couple of years, any of the oils mixed 32:1 to 50:1 are a good choice.
3) For my net-pulling planes which really work hard, I plan to switch to Pennzoil air cooled mixed at 20:1. This oil mix was rich enough to provide a lot of lubrication at these high engine temperatures and caused minimum carbon formation.
4) For my fleet of 12-3W-50 powered planes which run full throttle of 35 min but don't pull as draggy of sampling devices as the net planes, I will use either Pennzoil air cooled at 40:1 or 50:1 or Amsoil mixed at 40:1 or 50:1 (I have the Amsoil on hand).
At last a real written documented test to post. Looks to me like 5 ounces air cooled 2 cycle oil to a gallon (28 to 1 , what I use in my mostly well used hard working chainsaws ) falls well into the desired positive results. So do mixes up to 50 to 1 . Down to 20 to 1.
Does anybody know if something like his fleet of 12-3W-50 powered planes would have more or less stress then most chainsaw engines. Seems to me they would have a cooler, cleaner enviroment but how hard are their engines putting out full throttle for 35 minutes in comparison to bucking logs with a 70cc chainsaw ?