Just read this article: http://www.nightrider.com/biketech/oiltest1.htm
Shows Auto oil ran better in Jap bikes than the cycle oil. I ran Valvoline 20-50 in my Sportster 13 years no prob. but just bought an Evo (not twin cam) 1340 and was wondering how do non-syn oils stand up in the crank and primary on the evos? (Read the other article but everyone is listing different oils) I just want to know about oils such as Castrol GTX or Mobil1 or Valvoline that are made for autos. Motorcycle shops around me want $10-15 a quart for oil and ordering it is close to same after shipping.

 

I run synthetics in my Twin Cam due to the much higher operating temperatures that motor sees. My Evo seems pretty content on conventional 20w-50. Not that it matters, but I run Castrol GTX. I think you'll get a lot of the same opinion as more members chime in.

 

Yeah I read some forums that running full synthetic makes the seal weep (esp. the push-rods) after running dinosaur oil awhile due to the syn. cleaning the interior walls.

 

MANY opinions on this issue! I use regular 20-50 dino oil.....

 

My bike was a 14 year old police bike fresh out of police duty. I'm betting they only oil the police garage used was Harley's oil. So i used Valvoline 20/50 regular oil in it. It's the quietest Harley I have owned, motor wise. I've used synthetic oils before and always had more motor noice then I thought was normal. Plus saving some cash makes it a better deal to boot.,,

 

I was leaning towards the Valvoline 20/50 since it did good in my 1980 Sportster. But this is my first Evo and non-sporty. Didn't know how it would do (you know sportys share primary and trans. fluid) Thanks alot. Read alot of tests and believe I'll go Valvoline (Indian recommends it as an alternate oil)

 

20-50 Dino here too.

 

I won't use synthetic oil because as most of you recall,the MoCo years ago told us not to put it in a Harley,until they came out with their own and then they fully endorsed it.

 

Castrol GTX 20w50 for the last 18 years no problems here...84 never been rebuilt, still runs like new...now granted I change my oil a lot...but I only change the filter every other change....but the results speak for themselves.

 

Ran AMSOIL for 65,000 miles on my '98 Ultra til I sold it. Heard that because auto oil is designed for radiator motors, ( 30 degree temp swing,) while bike oils have additives for a wider range of temps, auto oil wasn't recommended. But I've never heard of any problems either way.I believe the biggest thing is regular oil changes.