Just did my own oil change, and after reading many posts on many forums, plus my experience with my Harleys, I used Mobile One 20W50 and the Bosch 3300 filter. The bike is running quieter and response feels the same as it did with the dealer installed Mobile 4T. The chrome cover fits the 3300 just fine.

OK . . so what exactly is the difference between the two oils?? Seems to me that the Mobil 1 should be fine in that engine . . . I ran it in my Road Star with the same type of gearcase/clutch connection . . . Why the 4T?

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Beer will save the world . . . I don't know how, but it will.

I've ran Castrol Synthetic 20W50 in mine for most of it's life. For some reason, I decided to try Amsoil 20W50 this last oil change. Don't really notice any difference or anything. I have noticed smoother shifting since about the 32,000 mile mark though..

Mobile 1 4T is a 10W40, which is what the manufacturer recommends. With the 10W20, I also experience smoother shifting.

You probably already know this but I'll say it anyway. As valves and seats wear the clearance is reduced.The engine will run quieter due to a reduction in valve train noise, and it will run great until the clearance is gone. Then you burn a valve.