Was running ATF in the primary due to an Alto Carbonite clutch pack, and non-ls dino gear oil in the transmission. Transmission and primary oil changed with the engine oil changes.

 

ATF should be Ok, because car transmissions have clutches like bike ones and they have chains. ATF will eliminate dragging clutch in cold mornings.

 

Anyone who has taken the time to read all or at least a substantial number of the oil forums - or maybe an oil tech here - able to explain the Primary Oil choice? I am under the impression the Primary is just a "Wet Clutch" application - any lubricating fluid is effective. More to the point, I have 24K on my bike, last 12K I have had Royal Purple in the Primary and it feels as if the clutch will not fully hook up. I cannot explain it - and I acknowledge this could be entirely in my head - but at highway speeds, I just have this feeling the clutch is slipping. Good connection on the low end, it is just the top end that gives me this impression.

Is it possible that RP is literally too slippery for this application?

I went RP when a guy at my local shop was explaining to the service writer that he (owner) knew what was leaking because he had purple in the primary, red in the trans, and brown in the crank. It made so much sense I figured I would do the same.

Anyone else running RP in your primary? What are your opinions?

 

Yes, it is slippery! Now you have 2 choices:
1. You can add sand to your primary to make oil not slippery
2.Replace weak spring. Check disks thickness just to feel smart, it is going to be weak spring anyway.

First one is cheaper.

 

Dump the RP and run any good 10W40 in the primary; might have to run for 500 miles and change again but any name brand 10W40 conventional will work fine in the primary. Some will insist the primary should be 20W50 which is fine but I haven't had any issues with 10W40. Redline Shockproof has always worked well for me in the trans and the fact that it is red does make differentiating between an inner primary or transmission leak easy is an added benefit.

 

NOT any Brand will work in the Primary! The bottle MUST SAY, NO Friction Modifiers, which is a M/C V-Twin oil! Don't use car oil, it HAS, Friction Modifiers!

Note; You can use Mobil 1, 15W50 car oil in a H-D V-Twin motor, BUT, NOT in the Primary!

 

Mobil 20W-50 V-Twin in all three holes, never a problem (Yet). "Buy it by the case".

 

OK, maybe I should have said "most" instead of "any" as I can't say for certain that all name brand conventional oils do not contain friction modifiers. However and FYI, zink and molybdenum (friction modifiers) are not contained in the any of the auto oils I have used. Avoid the oils labeled (energy conserving), sometimes marked with a starburst image as they do contain friction modifiers. I can tell you from personal experience that Shell Rotella 15W40, Valvoline 10W30 and 10W40, Castrol 10W30 and 10W40 and Mobil 10W30 and 10W40 all will work fine with the HD wet clutch. I am sure there are others but I know for a fact that those are fine for use in the HD primary.

Maybe you can enlighten the forum on which of the name brand oils still include friction modifiers and identify the friction modifiers? I believe you will find very few, if any.

Forum members, please do not be afraid to run name brand 10W30 or 10W40 in your primary; no harm will come from it.

 

Engine: Red Line 20w50
Tranny: Spectro Platinum 6-Speed 75w140
Primary: Shell Rotella T 15w50 (wet clutch certified)

 

i've used, the harley primary oil, 10w30 motor oil, 10w40 motor oil, 20w50 generic "racing oil", 20w50 harley dino motor oil and atf type f. 100k on the original clutch and i couldn't tell the difference in any of the oils i've used.