85W-140 Lucas in 8.25 Trac-Lok Warm Up Time!

[LibertyTC]

Man it sure takes a while to get the rear diff to warm up, more like free up Lol while using the Lucas 85w-140 with Chrysler friction modifier. I use this weight as I do pull the boat sometimes in summer & was told the thicker weight lube will help the 8.25 corporate assembly.
Any thoughts on how much extra fuel costs may be associated to thicker lube?
It is really noticeable when even slightly below freezing!
What is this stuff like... glue at cold temps?
https://www.lucasoil.com/products/display_products.sd?iid=44&catid=12&loc=show&headTitle=%20-%20Lucas%20Heavy%20Duty%2085W-140%20Gear%20Oil
No Pour Point listed..I wonder why LOL...
Ya I know I could use a synthetic...but really hesitate in that idea...
Need some feed back please...??
When this Trac-Lok clutch pack goes, going to go with an Eaton I think...
Or ..??

 

[Cardhu]

Even though i occasionally tow, i use regular napa 80w90 and change it more often.

Theres no way i'd be able to use w140 with the temps i see unless i start changing twice a year.

See how it does this summer; whenever that comes.