You'll find the detailed answer to that very question at the top of the Oil and Oil related topics forum in the first 'sticky' topic named What Brand Engine Oil do you use in your bike.

702 replies, 3755 votes. Last relpy was same day as your question, so it's still fairly current.

Answer: 9.85%

 

I use Amsoil - works for me

 

Mobil 1 syn 20w 50

 

I use 15w-50 Mobil 1 in my motor. I use the glue from this dead horse in my primary LOL!!

 

red line is an excellent oil. All there products are top notch. Red Line, Amsoil, Mobil 1 are all excellent. I hear Royal Purple is good too but have never used it.

 

ooooyyyyyyyyy!

 

That's one way to drum up business, promote Dino oil. I bet you would not recommend oil coolers on 88s,96s, 103s or any mild to wild built motors also. If you ride your bike put synthetic oil of the proper grade in. If you trailer your bike you probably could get away with a lesser oil.

 

So I take it you rebuild your engine every winter still. The newer engines have different alloys and Closer tolerances. Even the rebuild kits for the old engines are better engineered. All engines get improved with better engineered parts. The real world and users, expose components to non laboratory conditions. Use Motorcycle spec oils in motorcycles, PERIOD! But its your choice to spend a little extra now for Synthetic oil or alot later by using the current auto oil on sale at Walmart. I have ridden and raced bikes for over 40 years. The better you maintain your bike, the better chance you will not have a severe accident due to Drivetrain Failure.

 

I used to use Amsoil in my Sportster, but the Dyna doesn't like it so much. Amsoil suggested using the 20w50 in all three pots, but that didn't work out so well. The engine was probably fine, but the trans and the primary didn't like it at all. I went back to the HD formula + in the primary and Belray 85w135 in the trans and Screamin Eagle 20w50 syn in the engine. It feels better to me running on these.

 

This is one of those forum topics without end! I also have owned Harleys for donkey's years and have two at present, plus a Buell, which makes three. What oils did each come with from the dealer (I bought each of them new, in 1990 2008 and 2011)? Good ole fashioned stuff. If it is good enough for the latest Harleys it is still good enough.

I have an S&S motor in my old bike and they recommend using synthetic, so that is what goes in that nowadays, so my dynosaur uses synth, while my new kids on the block use dyno. They each work just fine thanks!