Originally Posted By: alarmguy
Anyway, all I am saying is people are putting true differential gear lube in their trannys, I personally would not do that. Because the transmission does not require differential gear lube any more then the engine does.
In Redlines case, I just learned they actually market a transmission oil that is different from their differential oil which further backs up what we are saying as Redline doesnt recommend their differential gear lube for Harley transmissions either.
Yet we have people all over the country putting Mobile 1 and many other companies gear lubes (not transmission oils or motoroils) in their transmissions, for me personally that is a poor choice, and not much different then if you put differential gear lube in your engine. [/quote]
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Opinions vary.
The Red Line tech recommends the 75W90 gl5 for the sportster trans as I have already posted his e-mail. says they have tested it with good results. Maybe you should e-mail him and tell him you dissagree and know better than he does.
Once again.
Thank you for contacting Red Line Oil, in the shared Sportster primary/transmission the 75W90 is recommended, a product that has been used extensively and performs well.
The 75W90 is the product we have have used for a number of years with very good results in Sportster/Buell transmissions, matching the viscosity and type fluid called for.
The 80W Motorcycle Gear Oil is a lower viscosity than called for, the ShockProof gear oils can due to their unique characteristics could cause sticking of the Harley clutches.
The 75W90 would be preferred and recommended over 80W Motorcycle Gear Oil in these applications.
There can be issues with some GL-5 gear oils in certain applications. Some can be corrosive to brass, bronze or copper, not an issue with our GL-5 gear oils, they don’t cause corrosion, pitting or metal removal. In a synchro equipped transmission the friction modifiers contained in many gear oils can make them too slippery, though not the case in a motorcycle transmission with dog rings.
So if you want the right viscosity and dont want to worry about it damaging anything, go with Redline
http://www.redlineoil.com/product.aspx?pid=133&pcid=4
also see.
http://www.hdforums.com/forum/sportster-...y-answered.html