I have had my bike for 15 years...nothing but Castrol 20/50 conventional car oil. In my opinion there are only 2 kinds of oil...clean and dirty...as long as you keep clean oil in it, they run virtually forever.

 

heavier oils decrease MPG but increase engine life

 

Agree 100%...syn is just a bunch of hype,

 

It wasn't that long ago that Harley was very much against using synthetic oil in their air cooled engines.

That didn't change until Harley started marketing their own branded synthetic fluid..

Imagine that...

My Harley Dealership mechanic friend has told me many times that they sell more HD 360 conventional oil than anything else, including the Harley branded synthetic fluid.

I'd bet that for every Harley running synthetic oil there are five times as many running regular HD 360 or Castrol GTX 20W50.

In all the years I've been riding Harley's I can't recall one occurance where there was major internal damage caused by the type of oil being used. Most engine failures are caused by operator error or lack of maintenance, not by the oil you are using.

Harley engines aren't very smart and as long as you change the oil and filter at reasonable intervals they are perfectly happy and will run almost forever.

It's the owner of the bike (and not the bike itself) that frets and worries so much about the specific type of oil being used.

 

79k on my Twin Cam using dino. She doesn't smoke or need oil added between changes. Until a while ago, I was getting HD oil for $1.99 a quart. 4 quarts and a black filter from a discount dealer made for a cheap oil change.