Changing the oil content of your fuel will sometimes require a change in the mixture setting. If you run the engine lean it will spin a little faster (higher RPM) untill it overheats and starts to move towards lock up and damaging metal scraping just prior to lock up. Now if you are using more oil in your fuel than before you may have to lean it some to get a propper run out of it. Just make sure you have that faint smoke trail coming from it and you will be fine. Remember if you have more oil conversley you have less stuff that burns.

The fuel I buy is 15% nitro content 18% synthetic oil which I bump up to 20% by adding natural castor. The gallon jug cost me about $16 USD. I am not aware of anyway to purchace any quantity of pure 100% nitro for self mixxing.