I am having some small issues with my transmission and am considering putting synthetic oil in my primary.
Does anyone have any experience with this?
Thanks

 

Lots of people run synthetic in their primary. You just want to make sure the fluid you choose doesn't have friction modifiers in it that could make your clutch slip. I look for fluids that have a JASO-MA certification (certified for wet-clutch use). I've been using Rotella-T 15w40 (non-synthetic) in my primary for years. A lot of people run Mobil 1 'Racing 4T' 10w-40 in their primaries, which is JASO-MA certified.

 

And you use the same oil in your tranny?
Sportsters have a shared primary/tranny.

Synthetic in the primary/tranny is fine, as said above, you just don't want one with friction modifiers. I've got over 100,000 miles using Mobil-1 75-90 Gear Oil.

 

OP didn't state what bike he had, so I wasn't thinking about a Sportster with a shared primary / tranny.


To be specific, in my 3-reservoir bikes, I use Rotella-T 15w-40 in the primary. In my 2-reservoir Sportster, I use Mobil 1 75w-90 gear oil in the primary / tranny.

 

Since this is a Sportster forum one would suspect he has a Sportster.

I use Red Line 75W90 synthetic gl5 gear oil in mine and will as long as I own my bike. It works great.

 

I've run HD SYN3, Red Line MT-90 and Red line 75w-110 synthetics in my primary/trans.

 

When using SAE 20W50 Syn3 H-D labeled oil or SAE 20W50, Mobil 1 synthetic motorcycle oil in the primary/transmission case, has the same viscosity as 75/90 gear oil, but the two oils use different scales.

These two SAE motor oils do not contain friction modifiers, less lubricity than SN rated motor oils for modern light trucks and automobiles.

Believe that Mobil Oil makes H-D SYN 3 20W50 full synthethic recommended by H-D for both engine and primary/ transmission cases.
Noticed much easier to locate store bought H-D labeled SYN 3 SAE 20W50 than store bought SAE 20W50 Mobil 1 motorcycle oil.

Amzoil wet clutch motorcycle oil is an excellent full synthetic oil used in common engine/trans or separate engine and trans configurations
and can be mailed ordered directly from Amzoil. It is a group 4, true synthetic base oil. The product packaging states no friction modifiers.

​​​​​Mobil 1 wet clutch motorcycle oil is a group 3, not true synthetic, hydrocracked crude petroleum base oil.



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What are these 'small issues'? Changing oil may not be a suitable solution.

 

Changing oil will NOT fix mechanical issues.

​​​​​​Noticed the back label on the Mobil 1 SAE 20W50 synthetic motorcycle oil has API (American petroleum institute) , SG, SH , CF & JASCO MA specifications and made in the USA
SG meets 1989-1993 auto manufactures requirements
SH meets 1994-1997 auto manufactures requirements
CF is for diesel engines

S is for spark ignition
C is for compression ignition

JASCO MA is Japanese four stroke motorcycles, non friction modified, further split into MA1 & MA2

Believe it is all right to use this oil in both XL engine & primary/trans, same as H-D syn3 SAE 20W50.

Noticed that H-D recommends a different primary/trans oil when using the H-D conventional group 2 engine oil in the engine.

 

Changing oil to fix a problem? Haha

Oil threads are worthless, these things will run with anything in their holes !

Factory oil suits my tranny, primary, clutch plates and 120 hp just fine