how about taking off the fuel line and sticking it in to a QUART of AUTOMATIC TRANSMISSION FLUID???? How about RUNNING the sled until the fuel pump sucks HALF of the ATF into the carbs and into the engine.. Your WHOLE FUEL SYSTEM,,, your BOTTOM END,,, your TOP END and your POWERVALVES will all be FOGGED TO DEATH and your WHOLE COMBUSTION chamber and POWERVALVES will be CLEANING ALL SUMMER!!!!!! it is somewhat of a BEAR to get the ATF out of the fuel system in the fall when you are ready to get her ready for the sledding season,,, but,,, it is a LOT LESS WORK than trying to CLEAN PILOT JETS and POWERVALVES when it's cold outside in NOVEMBER!!!!! AUTOMATIC TRANSMISSION FLUID has VERY GOOD DETERGENTS !!! have you ever seen a car with a trans leak (that has been leaking for a long time)????? Now you know what I am talking about!!!! No,, It really doesn't matter WHICH ATF you buy!!!!! The friction modifiers in different types WILL NOT DO ANYTHING to your sled motor!!!!!! (the CHEAPER,,,THE BETTER) Gary Oles nosboy