Had been using Royal Purple 75W-90 for the tranny since the bike was new since a mechanic friend recommended it. Now that the bike is older with 40K , as an experiment,
I decided to go back to the Harley regular motor oil brand. I hated it.

The shifting was much harder and the bike was noiser and not as smooth. To check
that it was not my imagination I went back to the 75w-90 and wow the bike was a lot more
smoother.

I use the regular motor oil on the clutch but after this I think I am gonna use the Royal purple also

 

That formula plus is only good for the primary. I like the Spectro 6speed synthetic oil its also really quiet and smooth

 

...Redline "Shock Proof Heavy" for me..but both are good...

 

+1 on the Redline SPHD

 

I have been using the Golden Spectro 6 for the trans and after all the reading on here decided to try the Shockproof Heavy in my tranny. IMO it is not nearly as good as the Spectro, in fact, not as good as Lucas Synthetic 75W90 gear oil. As soon as I find someone with the Spectro in stock I will be going back to it.

 

+3 on Redline shockproof. I'm sure there all about the same. Just don't use HD SYN 3 in tranny!!!

 

leave the motor oil in the motor put gearlube in the gearbox.the only place i would ever use v twinn anything is in the primary(v-twinn only means safe for clutch)so dont waste v twinn in the motor.

 

Gotta agree, especially on the Spectro 6

 

Good to know..that's what I use, Spectro HD Platnium 6 speed and good results from it. No 5th gear whine.
Heard that the lucas products especialy the "oil stablizer" was not all that is purported to be.

I used Royal Purple 20/50 years ago before it became popular and always thought that it was quite thin.

 

Why not?