I've got right around 5000 miles on my fluids . I am running Mobil 1 V-twin full synthetic 20w50 in all three holes . Recently I've noticed some hard shifting (harder than usual) . I want to change to something a little different . If I switch to ATF in the primary , which one is the best to use , and do I have to do anything after draining , or do I just refill ? Same goes for the tranny . I'm thinking of switching to either Royal Purple , or Mobil 1 gear oil . Is all I have to do is drain old , and then refill with the new ?

 

The choice on which fluids to use is yours and yours alone. The answer to your question on the Trans and Primary is yes...drain and refill with proper amount in ounces, acording to your service manual. Also, I use new O rings every time.

 

Right , I was just curious as to which ATF fluid would be best , and also , being that I am planning on switching types of lube....Would there be any thing I'd have to do before refilling . Like...Will the ATF mixing with the little bit of oil still left in the primary case , cause a problem ?

 

Just drain fully and add your new oil, mixing wont hurt.
I don't think changing from mobil1 20w50 V TWIN in primary to atf will benefit you in any way. I would change tranny oil though, to a synthetic gear oil of your choice-75w140 should be fine.

 

Okay , that's what I was looking to hear . I have been reading about ATF . Not sure if I will switch or not .

 

I've been using Type F transmission fluid in my primary (02 RKC) for the past 15k miles...changed once. Really good clutch engagement. Everything seems fine. I'm going to stick with it.

 

Try the Mobil1 75w140 gear oil in the trans. Then try some Mobil1 Vtwin 10w40 in the primary and 20w50 in the engine.

Should do the trick.

 

I run Amsoil Type F. Smilar to Trick Shift ATF Synthetic, Or Redling Primary oil.

20-50 engine oil is about the same viscosity as 90 wt gear oil. I don't figure HD primaries need that thick really.

Redline Shockproof in the transmission. Heaviest antiwear package available.

 

At my 20K a few weeks ago I switched the tranny to Spectra 6 speed 75-140. The harley only indy where I have things done that are beyond my ability recommended it highly. Said they have switched to it almost exclusively.

I think it quieted the tranny and the shifts seem smoother. Still have a little first gear clunk but not bad. After about 700 miles I think I prefer this over the previous HD fluid.

 

I changed my fluids this afternoon . Mobil 1 V twin in the crank case , 20w50 . Now here is where I deviated from the norm . I went with Super tech full synthetic gear oil 75w140 in the tranny , and Super tech type f ATF in primary . I have been using Super tech synthetic 5w30 in my car and I have 153k miles in 5 years on it , and it runs like the day I bought it . So , when I was in Wally world this morning , I saw it and I figured "What the hell" . I put 70 miles on it after the change . Shifts buttery smooth . Clutch seems to engage very sold , and everything sounds real quiet . I thought I noticed some excess heat coming from my primary , but it was about 93 degrees , in stop and go traffic , so , I digress .