Just did the 1000 mile service on my 2012 Fat Boy.
For the tranny I drained the factory fill Formula+ and refilled using Spectro Platinum 6 speed tranny lube.
Wow smoother more positive shifts, and less whine in 1st and 5th.
Honestly I don't understand using a basic oil like Formula+ in a tranny as any gearbox deserves a lube specifically designed for gear to gear contact.
Yeah it is $19.00 a quart but in my opinion well worth the money.
Baker driveline recommends it and now I see why.
This not intended as a which oil is better thread, and in fact if I could close this thread I would. My intention for this post is to give feedback on my experience so others who are looking for different alternatives can read this and make an informed decision.

 

Same reaction I got when I switched to Mobile 1 GL 75-90,

 

Good thing you didn't put a 5-speed lube in there. LOL

 

Welcome to the Platinum club...been running this "liquid gold" for the past 3-yrs and it's the sha-bomb of tranny oil's! Great stuff.

 

I just tired some in a pinch and it works fine, as does the amsoil gear lube I usually use. Either one works for me.

 

I agree with the assessment that tranny gear lube should be used in a transmission rather than regular oil and preferably synthetic gear lube too.

 

The sun, moon, and stars have aligned.

There is agreement on an oil topic.

The end of the world must be near, or hell has frozen over.

 

I just recently went with the 75/90 gear oil, and it improved the gear shifts quite considerably.
I'd like to try the 75/140 and will take a look at this Spectro oil.

 

Basically what it comes down to is as long as the gear lube is synthetic and made for gear boxes. After that it is all personal preference.
I just think using a multi purpose product like Formula+ in your tranny is counter productive to the optimal function and longevity of the transmission.

 

Since the tranny needs very infrequent oil changes it really does not cost that much.