i have allways mixed my own fuels for both satisfaction and savings but just the other day i had to buy 1 litre of mixed fuel for my sons r/c car engine. what happened was this new car engine would not start up very easily, would not run properly, would not idle, would run very hot when running, i really thought i had a bad engine so it went back to the store and the first thing the guy said was what fuel are you using ? i said a 20% oil mix of coolpower and castor 50 - 50 plus only 5% nitro in the total mix. he said straight away this is not the fuel to use in a high performance car engine [ Force 28 ] reason is they have an ABC piston / liner and the castor etc does not work, so he filled up the tank with some ready mixed car fuel and the darn engine started and run perfectly. i could not beleive it plus embarrassed dad with son looking right at me . so i,ve learnt my lesson in whats good for aircraft engines is not good for car engines.