I always used to wonder how the car engines got away with so little oil but after my son got a car and I saw how they were used I think it's probably because the engine only gets to peak revs for maybe at most 5 seconds on a straight, after that it's all on again off again....blat...blat....blat . Then they throw the engine away after a couple of hours use. However I talked my son into using 20% all castor because I don't consider an engine to be a throw-away item . So far it's only had about 2 gallons through it but there's not a trace of wear in it.