I know tis is a "run time" thread not a fuel choice thread, so I was hesitant to post. For the guys making comments on judging how lean an engine is by "how much it smokes" is not always 100% accurate. Sure it's a good way to be protective or observative, but the TYPE of oil that is used by a fuel company often determines how much smoke you will see. On some fuels, the engine can still be tuned too lean, and you will still see decent smoke. Same goes for the opposite, some brands can be rich, but you will still see barely any smoke. This isn't a "sell me thread" so I am going to just use examples, not advertising. Two totally different fuels can both have "9%" oil, but if different oils are used, the smoke characteristics will be totally different, including how much smoke and also the color of the smoke. A white smoke versus a blue tinted smoke even.

I use Sidewinder Team Stryke, and my pit guy/racing buddy uses Odonnel fuel. We both run a Reedy engine. At the same tracks on the same given day, my engine smokes more than his, every time, by I also tune my engines a little leaner, I know this because I also tune his. I tune them both by sound on the track, and the way they sound when they come into pit road after a practice run. Running Odonnel fuel, there are times I second guess the tune because I see hardly ANY smoke from his car, but I trust my ear and I know that he isn't lean although it looks lean. So the moral of the story is don't look at somebody else's car and judge how lean you think they are based on how much smoke you see.