75W90 in front diff

[iamweasel]

Hey guys,
I recently got my diffs' oils changed and on the receipt from the service centre, they've only listed 5L of 75W90.
I know the front diff is supposed to take 75W140. Assuming they have put 75W90 in both, what is the magnitude of the problem?
e.g. will the thinner oil in the front cause excessive where all the time - or only when in 4WD?

I just wanted to find out what you guys think before I phone the service centre.

thanks in advance for your wisdom

 

[TwoBobsKJ]

I don't think the lighter oil is a problem, per se. But if you do a fair amount of wheeling it would be better to have the 75W-140 in there. Or go to standard gear oil and put in 85-140 - much cheaper and easier to find.

If you specified 75W-140 and they put in the lighter weight then it's their responsibility to replace it with what you ordered. If you didn't tell them the heavier oil then you either stick with what's in there or replace it. Again, I'd recommend the standard gear oil vs the synthetic. Just my opinion though...

Bob

 

[sevenhelmet]

I run 80W90 in both differentials and it's been fine. I don't do a ton of aggressive wheeling, but my Jeep does see trails on the weekends.

Personally, I'd leave it. The differential oil really should be changed every 12-15K anyway.

 

[rockymountain]

75W90 is the norm. Its synthetic and really the only thing to "worry" about. Change every year if you use synthetic. 80 90 may be better since its dino oil and is really better in a diff than synthetic. I put 80 90 in both of mine over a year ago and its fine.

 

[iamweasel]

ok cool. Thanks for the responses guys. I'll leave it
I only questioned it because I had just recently read this HOW TO: http://www.jeepkj.com/forum/f202/how-change-your-front-rear-diff-oils-28670/

 

[tommudd]

75-90 is pretty standard for the front
75-140 for the rear if you do towing and / or off road
I have ran the above for 169,000 with no ill effects
although I do run good old Dino and no syn in them

 

[theroofable]

i use 75-140 in the front and rear. Whatever you put in will be better than the gunk that was in there.

 

[iamweasel]

Thanks guys