I've had good results with this in the past,, but now everyone seems to be running a 75W 140 instead. I've read that the 140 MAY be too thick for the 6 speed tranny. Anyone else still running Mobil One 75W 90 in a 6 speed?

 

I've been using Bel-Ray Gear Saver Hypoid Gear Oil in my older Softail and in my RK,,both 5 speeds but I've never seen any indication of wearing when I service them... I use 85W-140

There was a thread on here where some guys were saying the heavier weight gear lube leads to wear of the gears when the lube is cold & thick...

 

You might want to read up on how multi-grade oils work and what the first "w" number represents.

 

75w90 and 75w140 are the same thickness when cold. The 75w140 just thins less when at operating temp.
I've been using red line shockproof heavy in my six speed for 25000 kms and no issues yet

 

Been using 75-90 in all my Harleys since the beginning , now using it in a 2010 FLHTK , no issues .

 

90 should be fine up north...down here we need 140

 

I've used nothing but AMSOIL 75W-90 and had great results. If I lived in a year-round hot area I'd switch to 75W-140. Easy to buy on-line...

http://www.amsoil.com/storefront/def...i=1&zo=1791369

Still sold on Type F automatic transmission fluid in the chaincase.

 

Think they are using the 140 to quieten the 6 speed trans down.
At least that is why I am using it.
Dealer even told me to use it.

Barney

 

I personally like Formula Plus. I have used 75w90 and 75w140....Not much heat going on back there....as long as i have lube in there i am good.

 

Anyone try Mobil one 75w 90 synthetic gear lube in an Evo? If so, let me know how it works. I recently picked up a ‘95 Dyna FXDS with 17k miles. I plan to change all three oils. A poll in the Tech and Mechanical Forum ranks Mobile 1 pretty high. Does it smooth shifting and make neutral easier to find?