Most of the fuels out there now (I say most, certainly not all) are really geared toward offroad and short track onroad. They are perfectly fine for that but in my opinion and experience, they lack enough castor for 1/8th onroad on big tracks. If you are running on shorter tracks, any of the name brand fuels will work great for you. If you're going to a really big one, find one with at least 6% castor (that's 6% just for the castor, not 6% total and 7 might be even better) or add some castor to the fuel.
And just FYI, Byrons GenII 9% is only 4.5% castor.
Sean. Certified speed crazed mowron.
Team Shepherd USA