What is everyone using for their tranny/primary oil. Do anyone use the 75/140 and is it better. Just read a million posts on oil and its mind bogling. So what do I do, start another post.

 

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The 75-140 viscosity oils are for use in the Big Twin trannys where they have a separate oil supply for the primary and tranny. For the Sporty which has a shared primary and tranny, you want to stay with a 75-90 viscosity Gear Oil.

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Thanks for the info

 

Mac, I switched to Harley's Fornula+ from 20w50 Syn3 and can say without hesitation that it shifts quieter and better/easier.

The Formula+ stinks like two day old urine in the hot sun but does its job well.

 

Thanks 1200. I wanna try something new. Have a lot of clunking going on.

 

try red line syn gear lube in the tranny. its pink in color so if you drain the
primary & you see any pink at all you know you have a leaking seal between the tranny & primary.

 

Sporties have a shared primary/tranny.

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Just my opinion but I wouldn't want to use gear oil on a clutch.

 

Factory primary fluid works just fine in my 100 hp street stip bike, even after hot lapping at the track on 90* days. I had trouble when I tried switching. Any reason the factory fluid isn't good enough, I'd like to know why. You can be asking for trouble when changing. Factory fluid works fine with after market clutches too. Period