my experience is completely diff.

I first started running a special blend from condor models (otto cundra was the owner) his was a nitro of 15% upto 17%or 18% (might be off by 1%) anyway the main focus was having a lot of oil. 20% would be good. I no longer buy fuel from him and I have just switched to a 15%/20% 4 stroke fuel. Byron makes some. you can do the 10% with a high oil content and be fine as well.

I have 10 gallons through my rcv 120 and no problems (granted it has been a mix of 2 different kinds of fuel.)

on the RCV web site they tell you about expected rpms also. I would dis-regard this and just do tune for max rpm and temp. My rcv actually never got the 6k + rpms they talk about with the apc break in prop. I actually run my engine in 4800 - 5000rpms, I am now running the very scale "solo prop" 3 blade 18 inch adjustable pitch (I think I am running a 12 or 14 pitch.

all this is on a GSP Hellcat that is in the 11lbs range.

ps... I first read about these engines on RCU, it was a product review for the GSP corsair, on the box it said it would be 11lbs or more and that guy used the rcv 90 and he said it picked it up just fine. (in fact I understand that the 120 is just a bit more powerful than the 90.

my 2 cents.

mike