Mobil 1 75w-90. Synthetic, of course.

As you can see, the overwhelming majority use a gear oil over a motor oil, even though Harley wants you to use overpriced Syn3+ snake oil. Honestly, I have no real brand preference but I have used Mobil 1 Synthetic oils in every vehicle I have owned and its very easy to get. Mobil 1 has given me no reason to try anything else and if its not on sale at Autozone, it will be on sale at Advance Auto.

Also, those that have a "notchy" tranny, make sure your clutch is adjusted properly, as well as the cable. I always reset mine every time I have the derby cover off the primary. If you don't know how to do this, look in the service manual.

 

Going with amsoil 75w90 severe gear oil. The have it at fleet farm. Thanks for all the inputs.

 

Was using Redline Shockproof - I switched to Mobil 1 75-90 gear. It's okay but I think next change I'm going back to Redline in the tranny and stick with Mobil V-twin in the crankcase.

Jimmie

 

I switched mine for Amsoil 75w90 Severe Gear (from whatever Harley puts in there), hoping it would alleviate the occasional noisy, hard shifts. Made no difference as far as I can tell.

 

exactly. people hear what they listen for. Most synthetic oils are created equal, they are held to certain standards by the SAE. Likely they "hear" more when using a certain brand of oil because they want to hear it.

Viscosity is viscosity no matter the brand, it's not additives that quiet your trans down, it's the viscosity of the oil acting as a cushion between the gear teeth. You want a quieter trans, go to heavier oil, it's really that simple.