I would stick with oil that is designed for air cooled engines. I know auto oil can be used but dont know if there be any ill effcts. Better safe then sorry is my motto.

 

Any 20/50 full syn is bound to be fine. Big advantage is heat reduction and tolerance and they (syns) are all good for that.

EZ

 

But Nooooot in a wet clutch (primary)!!!!

 

Many synthetics are suitable for use in the primary with a wet clutch, it just depends on the friction modifiers used in the oil. Redline's MTL and new V-Twin Primary Case Oil are full synthetics and are specifically recommended for use in the primary. HD still recommends Syn3 synthetic oil in primaries, and thousands run synthetic oil of various manufacture in their primaries every day without a problem.

The recommendation not to run synthetics in a wet clutch system stems from a generalized belief that over a long period of time, moly (which is used in some oils) can embed in the clutch materials and cause the plates to slip.
I know a lot a of people who run synthetics in their primaries (including my 3 bikes) and I've never seen or heard (from a reliable source) of a single clutch failure due to slipping induced by moly in synthetic oil.

So while you may believe that some synthetic oils may cause problems over the long haul, to say all synthetics shouldn't be used is wrong.

 

rare, I agree BUT I wouldn't use motor oil in my primary anyway, unless it was cheap dino 10/40 without modifiers. Type F atf OR Redline MTL are the choices I make. The "motor oil in all three holes" nonsense is just that, nonsense IMHO. Redline HD Shockproof in the tranny or the Mobile one or Amsoil equivalent and something sensible and, hopefully , cheap in the primary.

Primary oil should be changed frequently, it isn't filtered and gets lots of contamination BUT is not in danger of overheating as the engine is. Therefore, using expensive syn oil in it is, IMHO , a waste and foolish. Changing it frequently is the best choice and type F and MTL are very clutch friendly and do fine on the chain.

EZ

 

If it says on the bottleto use it in the primary or is rated for wet clutches, then sureuse it, if not don't.
I would not be afraid to run a synthetic in the primary as long as itsa motorcycle oil and it says
ok for wet clutches. I wouldn't take a chance on just any thing off the Walmart Shelf though!!
Money comes to hard these days to take a chance on burning up a clutch pack.

 

well if you read this whole post ,its clear that you can run any type of oil in the primary.10/40 , 20/50, auto trans fluid dino or synthetic. the primary apparently doesn't care what goes in there as long as something is in there.if you can run the cheapest oil you can find and the parts last 20 years, whats the point of using $10 super duper synthetic oil ?

 

just make sure the oil for the primary does not say "energy conserving" on the specs... That is the additive that certainly causes the most clutch slipping.

$3 more for right grade oil there vs. $40-$100+ for a new clutch...+ time, labor, etc...

 

My point exactly, why try to savetwo or three dollars or put something in there that does not say'Safe forwet clutch usage'and risk being stuck and broke down on the side of the road. Get towed in and then spend hard earned dollars for a new clutch install. All for what?? Its simple don'tput something undesirable in where theclutches have to work and hold withoutslipping.

 

The belief that "spending two or three dollars more" is worth being "better safe than sorry" is what a salesman's dreams are made of. You guys make America work!!!