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Differential Oil Change

btfarm

btfarm

America First!
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Location
Sandwich, Illinois
I'm due again for a differential gear oil change. I went about 5k with the factory grape juice, then 110k with Mobil1 75W90 then another 70k with Amsoil 75W90. I've noticed it getting a bit 'grabby' in turns so I want to do a change. While I'm at it, I want to assure myself it isn't something with the Amsoil... which leads me to my question. I have done some looking around and it's damn near $11 per qt for the M1 75W90 synth now. :eek: I can get the Supertech equiv for about 1/2 that. I've heard only positive remarks about the Supertech oils these last few years and am tempted to buy 6 qts of it instead of the M1. Any comments?
 
I just did my rear differential oil change on my truck.

I was going to use amsoil till I saw the price.

I went to O'Reilly's and got the cheapest crap on the shelf.

Seems to be working fine so far.

I have a picture of what I used on the auto meter thread I had going.
 
from stuff I've read the super tech oils come from good base stock, which means the only difference would be the additive package
 
I've been looking at the SuperTech stuff too. It's synthetic and it meets the GM spec. If it meets the spec it meets the spec. I am running Amsoil front and rear also, but it is pricey and must be ordered so, shipping too. I am going to be using the Super Tech next go round.
 
IMO Amsoil is great for the engine oils, Nano fiber filter, greese. But you will be fine with the other fluid. Now if you were placing an order for engine oil....ect it would be a better time (Price wise) to include it on an order.
 
I run VALVOLINE gear oil and have never had a problem with the G80 being grabby in the turns. It has always worked well for me in any diff I have run it in. It's not the cheapest out there, but has served me well.
 
Dieseldad97 said:
All this talk is making me feel guilty not changing mine out yet. Thanks guys.
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You need to do that pal. You don't know what's in there do you? If it's still factory grape juice, it's not only nasty, it's at least a quart low (maybe 2 qts) in the rear.:eek:
4 qts rear, 2 qts front. Synthetic only. Take off the front skid plate and drop the spare for access.
 
Or just throw it on the lift and have fun. :wink:

I haven't had any issues with the Amsoil, I'll probably change it again next fall, it has nearly 50k on it.
 
FINALLY (!) got around to changing the rear differential last night from Ams Severe Gear to Super Tech Synthetic Blend. Both 75W90 wt. No grabby showing and I gave it some 'opportunities' to. We'll see the next few days with some warm weather and the windows down.
 
Lol, good to hear Mike. I have Thurs and Friday off next week, and Engine, Trans, Transfer Case and Axles are all up for fresh Amsoil.
 
Now that I've been running it for a few weeks I would have to say the 'grabby' condition is pretty much the same in a wet or damp pavement condition (which seems to be the right condition) and no sign of it on dry like it was. Could be it just wanted to be changed after all those miles (probably a good 80k+). I'm gonna do the front the same in the next few days, if I get time, with the same Super Tech.
 
Hey Mike! Good to hear the Super Tech is working. I have been noticing that the Super Tech 75w-90 is not available at the local stores here, just the 75w-140. I don't know if everybody is buying it up or my store just stopped carrying it.

I suppose going to the 75w-140 wouldn't hurt, but I don't do much towing at all anymore. Probably wouldn't notice any fuel mileage change either.

Thoughts?
 
I used 75W140 in the differentials of my '03 8.1/A and it later occured to me that was WAY too thick for below zero so I haven't done that again. Probably ok but 75W90 just SEEMS more the right way.
 
btfarm said:
I used 75W140 in the differentials of my '03 8.1/A and it later occured to me that was WAY too thick for below zero so I haven't done that again. Probably ok but 75W90 just SEEMS more the right way.
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I agree with ya completely, just having a hard time finding the 75w-90. Most of what I find is in the conventional oil, and I WON'T do that! If I have to I'll do Amsoil again, but I would like to try the Super Tech.
 
What I did is keep checking most times I happened to be at WM to see if there were enough on the shelf. I had 4 from 2 trips and did the change before I was able to get a couple more for the front. I think they must move alot of it. I'm also not 100% sure it's exactly the right stuff because it's a blend but at this point I decided to give it a go and see how it does for the cold weather. I don't know exactly how hot the rear gets in summer but I'd believe near 200* on a real hot day of towing so 100% synthetic may be the ultimate. I think next change I may consider going back to Mobil1 75W90. Had real good service out of that for 125k or thereabouts.
 
75W140,

First number is cold viscosity index.
Second number is hot viscosity index.

A synthetic in this weight will most likely cold flow better than Dino 75-weight oil will. But the real goodness is that it’ll only thin out at operating temps to what 140-weight dino oil would; in reality it has more to do with film strength and shear. (Caveat) this is a gross over simplification, a true definition can be found at the American Petroleum Institute www.api.org.

Long story short, I don’t believe you would see any significant fuel mileage decrease running group 4-5 full Syn 75W140 vs. Dino 75W90. The positives far outweigh the negatives going Syn, with the exception of some pre-90’s axle seals that have non-Syn compatible rubber. I believe at this point almost all automotive Syn fluids have seal conditioners added, as group 4-5 Syn like PAO’s can suck seals dry (leaks)!

Please keep in mind that since the big Exxon/Mobile lawsuit, then ironic merger, that not all synthetics nowadays would have been classified as such previously. Now a hydrocracked petroleum molecule is classified as a synthetic. Top tier Synthetics are still group 4-5 esters, olefins, PAO, Etc, which may have been chemically engineered from petrol derived feed stock, but were far more complex to mfg than a highly refined/simple hydrocrack’ed distillation petrol product.
 
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