My buddy just installed a new crate evo motor in his bike. Is it okay to fill the primary with standard 10/40 motor oil?

Also as I understand it 1 full quart should do the trick on a bone dry primary?

 

With the bike upright, fill the primary until the level is just touching the outside diameter of the outer clutch shell.

You can use 10w40 as long as it does not contain friction modifiers. If the oil is labelled as motorcycle oil you will be ok.

It is easy to tell if 30w and lower have friction modifiers, they are labelled as energy conserving. 40w and higher do not have that marking, even if they contain the slippery stuff.

 

throw some ATF in there.

 

I have a quart of Revtech SAE 20/50 that says safe for Harley Davidsons I was going to give him, but it does not have the Jaso certification or say its okay for the primary.

Thoughts?

 

Heard of lots of different fluids being used in a primary but never 20/50 unless you count Syn3. I'd just drop the money on whatever his preffered fluid is and call it good. No point throwing a brand new crate motor in something and then skimping out on the 10-15 bucks for some oil.

 

This is the stuff I have. If its okay I will tell him to use it.

 

Use it.

 

I hate oil threads, but you ask. Use Harleys Formal + since its a straight weight with no detergents in it. Designed for a non filtered system. The magnets there to mainly show a problem . If you use detergent motor oil, always use it. Do not worry about amount other then bring home enough. Do level. The clutch looks like an automatic transmission but the large inner primary bearing needs better (heaver) oil then ATF and also the primary chain will be loud with it.