I just bought a new Yamaha G-29 gas powered golf cart. The MFg says go 10 hours and change the oil. Recomended is 10-30, I will use it for the first oil change and go to synthetic after. Thinking of using a 10-40 HM because of the hot summers here in Florida and because the syn runs a bit thinner. just not sure about the high mileage. I'm told it wont bother it. Yamaha does'nt reccomend syn, but they did'nt for the outboards and I ran it in mine for 10 years with no problems. Ant thoughts? Thanks.