its down to percentage of nitro. the higher the number the more nitro therefore the more power you get.
depending on size of engine try to use 25%. but if it is less than a 16 engine i wouldnt advise 25% possibly 20 maximum if you use 25% on small engine you will need to shim it, i use 16% o my fazer with a 16 engine and it goes like stink.I use 25% on my ansmann virus which has 21 engine
its not advisable to mix brands due to oil content. good brands are as follows byrons gen 2 ,optifuel , monster juice