I'm feeling 10W-40 ams oil but that is just me.. AMS is a big racing oil and my friend uses it all the time on his 2 stroke ktm bike and his race snowmobile... they make a 10w-40 specifically forstreet bikes and even race applications.. it is a full synthetic.. It is just a preference..

 

smalltowbboy_08, is the amsoil line your talking about the MCF 10W-40 motorcycle oil with the crotchrocket on the front of the bottle? If it is, it is not specifically designed for "street bikes" but is only just "their" version of the JASO-MA rated "motorcycle specific" oils that is 10W-40. That would mean that their 20W50 is just for Harley's and big v-twins. It's all marketing I hate to tell you. I agree that there is nothing wrong with Amsoil products but like I said in my prevoius arguement, why pay 10 dollars for a quart of oil that will shear out of grade faster and provide the same wear results based on a used oil analysis as a 2-3 dollar HDEO would provide?