WOW....you are opening up a can of worms. You'll get every opinion imaginable. A lot of people here use Rotella, some use Amsoil, some use just about everything else. The main thing is that you don't use a regular automotive oil with friction modifiers. They can cause your clutch to slip. I personally use nothing but Mobil 1 Racing 4T motorcycle specific but it's about $9.00 per quart and some think that is a waste of money. I love Mobil 1 though and use one version or another in everything I own.