hey Tom.. I have a Yamaha G2 golf cart also and just filled the rear end with oil. The drain bolt is on the drivers side toward the rear of the trans, get a flat pan under it and remove the bolt. Jjack up the front end and you'll get more out. Let it drain for an hour or so, its thick so it takes awhile.. Leave the bolt out and yank the vent tube directly above the drain hole. Lower the golf cart and put in sae 90w gear lube. It too is thick so squeeze it in slowly...when it starts to come out the drain hole, put the plug back in and you're good to go! tube back in of course..