It is not really the cost for me, I simply want the best product/solution for my training operations. I changed from Aeroshell 4 to Amsoil motorcycle fully synthetic because it was highly recommended here on this forum and my 245 hot day climb oil temperatures could be reduced. Well I switched and the oil temperature went down by 10 degrees (I also used the amsoil coolant boost at the same) which may have helped. Wonder if there has been any improvement in the new Aeroshell 4 formulation that will help the engine run cooler.