hi  been flying and repairing glo engines for 20 years   started out using full syn glo fuel and found much more wear in the early days than when i switched to a castor -syn mixkeep in mind that castor oil breaks down from heat  100 PLUS degess over the syn oils-so you are protected  when (not if ) you run you  glo engine a bit lean on a particular day-there now doesn't that make you feel better-better to clean your plane than to cook your engine any day