There are probably more threads on oil around HDF than any other topic. Your sport bikes use only one oil - Harleys use three different oils. They both come that way from their respective manufacturers for a reason! Jus' sayin'....

 

And the reason is same oil lubes everything in metric's...where HD's have evolved with seperate trans, primary drive and engine components bolted together

 

I have been told you can run the same oil in motor,Primary and tranny as long as it is 20w50 fully synthetic.
Is this right or do I need to run a gear lube in the transmission.
This is on a 2007 Dyna FXDB

 

You can run it in all three holes.

 

You should probably ask Caitlyn Jenner which lube is preferable.

Syn3 is ok, but I noticed a bit more noise than what I thought was acceptable. And changed to Amsoil Synthetic Gear Lube 75w/90, which seemed to work the best for me. I've also used Red Line and Royal Purple.

 

Mobile 1 in all holes.

 

 

Last change I used the Synthetic 20w-50 in all 3. I now have trouble getting the tranny into neutral until it is good and warmed up. I am going to change back to thinner tranny fluid.
No problems with the clutch and engine, though.

 

I use Mobil 1 Full Syn 75w90 in the tranny. Mobil 1 20w50 in the crankcase and HD Formula + in the primary. Seems to give me the best overall combination of smooth shifts and smooth clutch. I've never tried 20w50 in the primary but I hear it works well.

 

I have tried them all and have had the best luck with Formula+ in primary and tranny, Mobile 1 V twin 20w50 in the engine. I would not recommend Synthetic in the primary. I also use a Scavenger oil change system to remove all used oil from the engine. My FXDWG has 90K trouble free miles and I just hit 20K on my new Roadglide. Both run cool and quiet with clean shifts.