Synthetic Oil

don't forget the anti-freeze. don't mix the dif. type. If you mix the green and the orange you will have a brown mud like substance that don't circulate very well. also synthetic oil in a older model H-D and you will be spending big $$$$ rebuilding the motor. They have ball bearings in them and the synthetic is to slick for them to roll and rotate. they get hot and lock up. not a good think. Not 100% sure,but I think tranny fluid has the same issues as the oil