i use synthetic ATF in my primary. ATF is formulated for clutch discs. the fluid in the primary lubes the chain and pulls heat away from the clutch basket.

 

Gear oil is graded differently than motor oil. 75-90 gear oil would be about the same as 10w30 motor oil. Lots of people use gear oil in their primary, and I don't recall any saying it caused a problem. I do agree that ATF is a good idea in the primary, and because I use it there I know my primary is leaking.
Since it's already in there, run it.

 

75/90 is not correct but it wont damage anything...however you should change it

I highly recommend B&M Trickshift ATF (black bottle) for Primary Fluid

2 qts are needed because the 07-09s hold more ... 38oz when just changing fluid & 45oz if you remove the cover & open up/drain the clutches.

If you're comfortable with doing it, remove the Primary Cover, clean out all the 75/90 oil, pull in the clutch lever & hold it open with a rubber band or something & let it drain out before you change the fluid out. Its not required but its a good practice ....


Jim
www.FastAire.com

 

DOGCOP - Well it looks like you have about as many people telling you to change the primary fluid as there are those telling you to leave it alone. So its a matter of what you choose to do.

You have a sizeable investment in your bike. If your like the rest of us its around 20K. So if you have any doubts go ahead and spend the extra ten bucks or so. You'll probably sleep better at night as well!

The idea of putting ATF in the primary makes good sense to me although I'd never heard of it or thought of it before. Its also probably less expensive than the other products mentioned.

If you go to the dealership they will sell you the same product for both the tranny and primary - Formula+ - so there's something else to think about. Personally I like the RedLine shockproof in my tranny and I noticed a distinct difference with the RedLine MTL in my primary.

As far as my comment on Amsoil - that's just my opinion. A lot of other people out there swear by Amsoil. I am not one of them. Every mechanic I spoke with when having my engine rebuilt said the same thing - you change the oil when it is dirty. Different driving conditions like stop and go traffic or riding in normally hot climates will affect how often this happens. Today's engines tend to be smaller, run at higher RPMs and run at hotter temperatures with hotter thermostats. This causes oil to break down faster and sludge problems develop. Do a google search on "engine sludge" and see how many hits you get.

Our Harleys with their air cooled big twin strokers run at 240 degrees head temperature. It doesn't matter what kind of oil you put in there - synthetic or dino, Mobile 1, Amsoil, Redline, Castrol - you name it, its going to break down and need changing more often. So watch that dipstick.

Okay, sorry. I got off track. Your question related to oil in the primary not engine oil. I think you've probably got enough info here to make a more informed decision.

Good Luck and Good Riding - Enjoy your trip!

 

I agree with AustinRider. Either way you will be fine. The service manual shows the same fluid in the tranny and primary (if I remember right, don't have the book with me) and they are both gear oil not motor oil. I am running synthetic 10w30 (Penzoill I think) in mine right now because it was on sale for $4.99 a quart at O'Reilly's.

 

just wanted to say thanks for all the great advise, i did change the oil out today and put in mobil 1 20/50 just so i can make sure i don't screw this up again. i love the forum because whenever you have a problem you will always find people willing to help you out (even if i ask stupid questions). thanks again to all.

 

Give the Redline Primary lube a try. It is a synthetic, and does a fine job. My 03' Screamin Eagle deuce was dynoed at just about 100HP/100TQ, and in the last 2500 miles with the Redline it hasn't slipped one bit. IIRC RedLine has changed the name from MTL to V-Twin Primary case fluid....but AFAIK its the same as MTL.

BTW: I also use Red Line 20/50 V-Twin in the engine, and Heavy Shockproof in the tranny. Both fully synthetic

 

Just dump it and put in some 10w30 napa brand cheap *** dinosaur oil. It will work great!
Hell, drain the gear lube, add the 10w30, ride it till it's nice and hot and then drain it again to make sure you get that thick *** gear lube out of there. That's what I'd do. I've actually read that synthetic in the primary is almost too slippery and may cause clutch slippage.. who knows. Cheaper is better in this case, it seems. Ride on buddy!

 

Ref: Using ATF in the Primary - just some info.

Several clutch co's like Barnett recommend using ATF-Type F as a primary fluid. An auto's automatic trans is a hostile enviroment compared to HD primary enviroment so it will hold up with no problem. Its a fairly cheap alternative to HDs & others primary fluid & real easy to get, except for B&M which I use at about $7.00 a bottle. Some clutch co's do not recommend using Auto Syn Oil due to friction modifiers that "could" promote slipping... but opinions vary on this one because many bikes circulate the motor oil in the trans & clutch area.

There is also varying opinions as to the correct weight oil for the Primary ... 10w-40, 20w-50, 30wt, ATF.... blah blah. Ive used 20-50 dino oil & ATF will good results

Anyways... just sharing some info. Do what makes ya happy


Jim
www.FastAire.com