Ive done alot of research but havent run across the question i have.

I recently put valvoline full synthetic 75w-90 gl-5 in my tranny.
I made 2 mistakes. 1st I shouldnt have used synthetic. 2nd I shouldnt have used gl-5
Ive run less than 100 miles with that oil
It started to shift very rough in 1st and 2nd
Lesson learned

I orderd Red Line MT90 75w-90 gl-4 gear oil that everyone recommends.
Thats what i am going to put in the tranny to fix the problem.

The front and rear axles need a gl-5 gear oil.

My question is:
Can i use the synthetic 75-90 from the tranny in the axles.
I know its unorthadox, but ive put very few miles on the oil and it was expensive.

its a 1991 pickup 4x4 r150f tranny

 

pretty sure ya need a hypoid gear oil in the diff

straight from 4crawler...



Fluid Specifications
Type Grade Amount
Gasoline 87 pump octane unleaded
(=91 research octane number) 17.2 gal.
Engine Oil SF/CC, 10W40 4.9 qt.
Coolant Ethylene-glycol 8.9 qt.
Manual Transmission GL-4/5, 75W90 22R: 4.1 qt. 22RE: 3.2 qt.
Transfer Case GL-4/5, 75W90 1.7 qt.
-Dual Transfer Case GL-4/5, 75W90 +0.7 qt.
Front Differential Hypoid GL-5, 80W90 2.4 qt.
Rear Differential Hypoid GL-5, 80W90 2.3 qt.
Power Steering Automatic Transmission
Fluid - Dexron or Dexron-II ~1 qt.
Brakes DOT-3 ~1 qt

 

says right on the bottle :
"recommended for all standard and limited slip hypoid differentials(conventional and high performance applications) and manual transmissions where an API gl5 or mt1 fluid is specified"

 

THEN...YES you can use it... I run the Lucas 80-90 Hypoid compatible in mine. works great. Probably wouldnt hurt anything even coming outta ur tranny.

Personally I wouldn't tho cuz diff fluid is less than 20$ total unused.

 

ok thanks. the reason i asked is because it is in my tranny right now. i dont want to just drain it and not use it. seems like a waste. i havent put many miles on it so i figured it would be a big deal.

 

When you drain it... put it in a crystal clear container... let it sit for a day.... see what accumulates at the bottom. if it is clean ... use it. if there is metal or anything in the bottom... make sure none of that gets in ur diff. lol

money saved is gas in ur tank and food in yer belly.

and i am CERTAIN once filterd/settled clean.. it will be in better shape then what is in yer diffs now. so why not..

 

GL-5 will work fine in the axles. Should have almost enough from the trans. to fill the diffs. Just make sure to use a clean pan to catch it.

 

haha thats true.

and yes it probably is alot better than whats in there now. im the 3rd owner and the truck is at over 200,000 miles. who knows when the diff oil was last changed.

thanks again. just wanted to get a few opinions cuz its really not a normal thing to do