Running heavier weight gear oil? (1 Viewer)

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Wonder if anyone has used gear oil heavier than 80W-90 in their differentials and what they've noticed if anything??
 
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What's your reason? Having a hard time finding the correct weight oil cheap?
 
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I've been getting a light roar or moan under load that is in direct proportion to road speed; the faster I go the louder it gets, and it goes away as soon as I lift my foot off the gas. Talked to a local independent mechanic who's pretty sharp; he thinks the noise is likely from wear in the rear pinion and ring gear (front driveshaft is out). So I was thinking of putting a heavier gear oil in the rear diff to see if the noise changed; if it did I would know that's where the problem is and it might buy me some time. But also wasn't sure if I used say 80-90-140 whether it could cause a problem?? Hit me.
 
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Oh, ok. Sometimes i have trouble finding the correct weight oil.

On the other hand you can pull the third and tighten up your carrier bearing pre-load and see it it helps out. Assuming yours is not locked. Normally the gears dont take a dump unless the bearings go first.
 
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During the summer I run 140w gear oil in the center diff it really smooths out some of the typical 80 clunk
I still run the regular stuff in the diffs
 
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I've got a quart of that Lucas Heavy Duty gear oil that's just sitting around, could dump that in the diff and see if anything changes. On the other hand IIRC there was a long discussion on Lucas a couple of years ago; seems to change the gear oil white or something??

Found the link about Lucas additives. Cary (a lube guru) used to be on the forum often.

https://forum.ih8mud.com/80-series-tech/99744-lucas-additive-big-difference.html

Kidglove: OK, that's good info; just wasn't sure what the effect would be by going to so high a weight.
 
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Its a pretty penny but Mobil makes a "75W 140" pure synthetic oil that would work year round and when hot will act as heavy as anything out there without sacrificing cold performance. I think it is a really ridiculous $15 a quart IIRC! Hope that helps. :cheers:
 
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You could always mix 90w and 140w I have done that before as well seems to quite things down alittle
Diff oil is cheap you could always experiment as I have, cant hurt to try
 
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Its a pretty penny but Mobil makes a "75W 140" pure synthetic oil that would work year round and when hot will act as heavy as anything out there without sacrificing cold performance. I think it is a really ridiculous $15 a quart IIRC! Hope that helps. :cheers:

I wouldnt run the 140 stuff if the temps in the winter months are below 35 degrees it just gets to thick whether it is syn or conv.
at least that is what I have found
 
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That was my thinking also; currently using Mobil 1 75W-90 and might go to half 75W-140 in the rear differential, temps outside are warmer now. Yeah, the prices for the Mobil gear oil have really gone up, guess I could experiment with some Wally World cheapo gear oil first.
 
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Forget the Mobil stuff, a waste of money in my opinion
Regular old conv from wally world is the ticket or coastel gear oil which is what I prefer
In the past at one point I had two nice performance cars the nicer one got nothing but full on Modil 1 treatment and the other got good old conv stuff.
There was no noticable difference in performance and the difference in engine wear and sludge build up was marginal when I had the heads off of both vehicles after 150k for performance mods and such
Is it good stuff I would say so but not what it cost per quart better and the same goes for the other syn stuff as well.
What did they do before syn oils were around? Good old conv.
Just my 2 cents
I am sure plenty will disagree
 
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Truth be told I don't like the job of draining and refilling the diffs and with the Mobil 1 in the transfer and rear diff I've run it about 80,000 miles already, it's about time to change it out. I use Wally World semi-synthetic 75W-90 at half the price of the Mobil 1 in the front diff due to possible contamination from the knuckle grease and change that a lot more frequently.
 
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I got it
That is the one plus of syn it does not break down as fast as conv.
I like to change my junk alot more often
I put alot of miles on my truck and I wheel it pretty hard as well
I change my diff and tcase oil about 3 times a year.
 
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It is doubtful that your ring and pinion is making noise.

It is far more likely that your pinion bearing(s) are the source of the noise.

Running heavier gear lube will not solve anything.

I run 75-140 in rigs I expect to leave it in... and whatever I have on hand for rigs that see a lot of changes due to water contamination (these rigs also do not see a lot of highway miles or any towing duty beyond a loaded M416).


Mark...


Mark...
 
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It is doubtful that your ring and pinion is making noise.

It is far more likely that your pinion bearing(s) are the source of the noise.

Running heavier gear lube will not solve anything.

I run 75-140 in rigs I expect to leave it in... and whatever I have on hand for rigs that see a lot of changes due to water contamination (these rigs also do not see a lot of highway miles or any towing duty beyond a loaded M416).


Mark...


Mark...

Ditto, it's only really mask the problem.

I run cheap diff oil since it's subject to contamination. However I run redline in the xfer case. Redline/synthetic made a big difference on cold shifting and hot temps on my W56's on the minis.
 
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Thanks for the opinions; the idea of adding the heavier weight gear oil was not to fix it, just to see if the noise changes to maybe help narrow down where the problem is, rear diff or transfer. Need to pull the rear driveshaft also when I find the time.
 
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Wonder if anyone has used gear oil heavier than 80W-90 in their differentials and what they've noticed if anything??

I only run 85W-140 in my difs. It quiets down the aussie lockers.


Running heavier gear lube will not solve anything.

I've run 85W-140 in three 80's that have all had aussies in at least the rear axle (now in the front too)... it solves loud clicks.... the heavy weight soothes auto lockers. So, yes, it does solve something.
 

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