I recently put the new 80w140 synthetic in my '18 Heritage transmission and primary. Had Syn3 and Formula+, respectively before. I've also used Mobil 1 Vtwin in the primary. It's definitely easier to shift into neutral with the new oil. I did not adjust the clutch so it's a direct comparison. Always before there was enough resistance coming out of first that I would sometimes pop through neutral into second. Now it shifts into neutral smoothly and predictably.

This is a bit more subjective but I would say that the clunk into first when cold is less pronounced and shifting overall is maybe a bit smoother. It's also noticeably easier to push when cold and in gear with the clutch pulled in.

I'm skeptical of claims about being able to "feel" improvements from changing oil or air filters, type of gas, etc. but in this case there's a definite difference.

 

I've always advocated a heavier weight gear oil in our transmissions to be honest .

Peace.

 

So its ok to put 75-80w-140 in the Primary?

 

HD is now selling a 80w-140 synthetic for all transmissions and most primarys. It's on their website.

 

I have a 2019 Triglide with a Rekluse clutch. When shifting I can hear a whinning sound. I spoke with a tech and I was told to try the new HD synthetic heavy gear in the transmission hole. Now the whinnying sound is down 90 percent. Btw the bike was checked and HD tech said the sound is normal prior to changing to a heavy gear out. It was an annoying sound versus a mechanical issue.

 

Just serviced my bike with it, seems to be much easier to get into neutral and I think it shifts a little nicer, but not a dramatic difference otherwise.

 

I wrote this review for my group and the Ultra Limited group on Facebook end of May '19.

Review: Harley-Davidson Gear Oil.
This is a relatively new product to market, maybe 6 months

2019 FLHTK with 114 Stage 1 and Stock 6 speed, clutch and primary components.

Changed out initial Formula+ on both Transmission and primary at the 1k mark then replaced with the H-D Gear Oil. The transmission loves it. No gear rattle, etc. The clutch is a different story. After the initial change-out of fluids, I would periodically notice what felt like a clutch slip in 4 and 5 under heavier acceleration (above 4000RPM), it would not do it all the time, but it would happen to the point where I was starting to be more gingerly with my 4th and 5th gear shifts. Had my daughter on the back and she even would say "what was that?" when it would happen. Then under slow acceleration and maneuvers the bike would get stuck coming from 1st gear to neutral and would not engage 2nd unless I increased the throttle or would pre-load 2nd gear buy putting pressure on it with my toe, again it didn't happen at every shift. I drained out the H-D Gear oil from the primary replace with formula+ and have ridden now about 350miles and have not exhibited the issue at all, and I've been trying to get it to do it. Long story short, it seems the M8 clutches prefer formula+ as all other H-D compensators and clutches have always hated synthetic oil. Stick with formula+ in your primary my friends.

 

My hydraulic clutch feels good and bike shifts into neutral with a bit more ease with the 80W-140.

 

I gave in to curiosity and swapped my trans fluid and primary fluid to the new HD stuff. Works fine and seems to shift smoother.

 

LOL, maybe HD released it to help with the tranny fluid migration, being it’s a heavier viscosity, haha.. as we approach roofing tar viscosity, nothing will migrate!!

All jest aside, I’ll try it on the next fluid change. What’s another twenty bucks...