What octane gas is best for the Evolution 58gx2? I have been using higher octane gas in my 45gx2 for 3 years and it is a great engine. The book is not clear on the octane for the 58cc, I have tried both and it still does not run as good as my 45cc. It has about 5 gallons of gas run thru it and I am using redline 40:1. Last week it ran great the first flight and after that it would not crank or it would not run over 5 seconds. The factory setting for the carb are 1&3/4 turns and I stay within 1/2 turn of that setting. I have two gas tanks that I rotate every six months to make sure the Tygon does not get stiff. I am using a 7.4v 2600mah Lion battery and a Mejzlik 24x10 prop and have never gotten over 6000 rpm. I finally sent it to Horizon last week. I am hoping they can find the problem.