Not looking for the best, just curious if anyone has found one that quiets the primary down?
Form+ for me
...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.. :wink:
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.
Spectro and Bel Ray primary fluid have done very well for me.
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..
(https://live.staticflickr.com/65535/51465204761_e1cd18d179_c.jpg)
So I buy the one I can get the best price on. So far, it's been the Gear Saver Trans oil...
Good to know,as I use it lots with performance clutches. :potstir:
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
I assume the heavier the weight the quieter?
Looks like spectro is 85w
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.