Primary Fluid

[NHBagger]

Not looking for the best, just curious if anyone has found one that quiets the primary down?

[road-dawgs1]

Form+ for me

[ViseGrips]

...back in the MSN days there was a  gentleman here on HTT  who was using a semi synthetic 75 w 90 gear oil GL5 ,,Military M1 grade in his primary...he was saying it had a pour factor of a 40 weight some shearing stabilities and would also help in keeping the stator cooler...I started using it in my 99 FLHTC and I found it pretty dam good..also used it in my 2005 FLHTC .I could obtain it at Canadian Tire/their brand /Motomaster ...but a few years later it was discontinued and /replaced with other brands of full synthetic gear oils...these days I use the Formula Plus or Lucas primary chain case oil in the primary...but not in my tranny...tranny gets 75 w 90 synthetic gear oils...my bike was relatively much quieter than many around me for any related noises back then .  ..opinions may vary on this subject..   

[Hossamania]

I've run just about everything in mine, Formula+, Spectro Primary oil, etc. I'm now running Amsoil 20w/50 motor oil in one, cheap O'Reillys type F tranny fluid in the other. Couldn't tell you if any one is quieter than the other. Once hot it's all pretty much the same for me.

[calif phil]

Spectro and Bel Ray primary fluid have done very well for me. 

[hattitude]

I saw a recommendation on this forum I believe, to use Bel-Ray Gear Saver Transmission oil (80wt) in the primary. I started using it with no issues. Seems to work as good as the HD Formula +  which I had been using.

I saw an add for Bel-Ray V-Twin Primary Chaincase Lubricant, but it was more expensive than the Gear Saver 80wt Trans oil. I also heard a rumor that the two products were very similar...

So I contacted Bel-Ray via email to ask about the two fluids. This was their response..




So I buy the one I can get the best price on. So far, it's been the Gear Saver Trans oil...

[RTMike]

Good to know,as I use it lots with performance clutches.

[Norton Commando]

I have been using Mobil 1 Racing 4T, which has a 10W 40 viscosity rating in my 2012 FLHTK and I don't hear any abnormal noises from the primary.  Notably, I used ATF in my EVO primary for over 20 years and didn't hear any abnormal noises.

Jason   

[NHBagger]

I assume the heavier the weight the quieter?
Looks like spectro is 85w

[Tacocaster]

Yes, the heavier the quieter until the stator burns-up.
I use Redlines' Primary Fluid and their Gear Oil as well and have no issues with any noise or neutral-hunts or Stators.
Like Hattitude's Bel-Ray, same product in different wrappers according to Redline.

Buy what ya like. Just be aware of the requirements.