Fishaddict it is exactly what it says. Air filter oil. These are two stroke nitro engines and need the filter to be cleaned and oiled with a range of oil that will work in order to catch the finer particles from getting into the engine and causing damage. The best types of oils to use are the k&n filter oil or a can of dirtbike airfilter oil from the motorcycle shop. You can even use motor oil. I use 3 in one oil myself. You need to clean and oil your filter every 4-6 tanks depending on driving conditions and ground. Also you dont want to over oil it so that the carb sucks loose oils into engine you just want it damp enough to help catch dust.
