I'm changing the fluid in my front and rear differentials this weekend. I've heard that for our trucks...we have to use 75W90 in the rear differential. My local auto parts store only had this brand and only in 85W140. Is this okay to run in my rear differential...or should I find some 75W90? If anyone knows, please let me know!

Thank you!

http://www.autozone.com/images/products/ctl/ctl12301003.jpg

I would recommend going with either 75W90 or 75W110 synthetic gear oil. If your local parts retailer doesn't have it, I would buy it online from one of the vendors here. I'm sure Heath and the other lubrication vendors on this site would take good care of you.

Should be able to find some Mobil 1 in 75W-90

:saluteusa:

I would stay with 75. If it were the other way around(need 85,but use 75), you'd be ok. I would highly recommend a synthetic gear lube, not necessarily mine, but just a synthetic. Petroluem gear lubes are pretty much old hat and don't offer near the protection.
Here's a study showing several and how they compare:
http://www.amsoil.com/products/gearlubes/WhitePaper.aspx
Heath

I would stay with 75. If it were the other way around(need 85,but use 75), you'd be ok. I would highly recommend a synthetic gear lube, not necessarily mine, but just a synthetic. Petroluem gear lubes are pretty much old hat and don't offer near the protection.
Here's a study showing several and how they compare:
http://www.amsoil.com/products/gearlubes/WhitePaper.aspx
Heath

Skimmed over that paper, and I was unsurprised by the results. Amsoil came out on top, and Royal Purple and Lucas are junk.

I would have liked to have seen Schaeffer's included in the lineup. I think they were left out so that Amsoil could come out on top ;)

Maybe??
Honestly, I'm sure it was just because they had to limit the number of brands and Schaeffers is smaller than the rest. If going for market share, you've got to show up the big ones.:)

Go with synthetic front and rear for sure. Keep looking. You need 75/90 or 85/90

Moving to the fluids section.

I completely missed the fact your picture was a 140 weight. Sorry. The 140 will work. I know people that use it,but it's overkill. More drag will decrease fuel economy. The 110 mentioned earlier is a great choice, but so far, we are the only ones who make one:)

My manual says synthetic 75w90...it's in lots of auto parts stores.

Skimmed over that paper, and I was unsurprised by the results. Amsoil came out on top, and Royal Purple and Lucas are junk.

I would have liked to have seen Schaeffer's included in the lineup. I think they were left out so that Amsoil could come out on top ;)


How did you determine that RP Lucas are "Junk"?

Lucas failed or didn't meet the requirements on five of the tests. Had the worst total score and RP had four. It scored second to last. And depending on which test it didn't pass, it could really bring down the total effectiveness or protection of the lube itself. The GM oil came out 3rd, but yet had the worst foaming in the oxidation test. Foaming can be a real concern and rendor a lube ineffective depending on the severity.

How did you determine that RP Lucas are "Junk"?


True story: I work in an industrial plant that has pumps/motors/gearboxes what have you that run 24-7-365 (for the most part). Every time we put royal purple "synthetic" in something it has turned to sludge and caused something to break. Since switching to Mobil we are not seeing that happen anymore. RP is overpriced to start with, and after it causes mechanical failures the costs just escalate.

I had no problem finding Mobile-1 75/90 at Advance auto parts. $8.98 :eek:a bottle.

Yeah, I went to Advance and bought 6 bottles of Amsoil 75w90 and it ran me about $55

Im swapping in an ATS diff cover this weekend...anyone know the capacity?

Edit: the ATS pan is +2.5 quarts, but what is OE level?

Im swapping in an ATS diff cover this weekend...anyone know the capacity?

Edit: the ATS pan is +2.5 quarts, but what is OE level?


Fill it till comes out the hole. OE capacity is approx 4 qts.

Fill it till comes out the hole. OE capacity is approx 4 qts.


10-4, thanks.

I recommend mobil 1 75w 90

Royal Purple is the most overpriced/under performing oil on the market.

I try not to comment on other brands, but would tend to agree with this. Before buying, be sure you've taken a look at the comparative study. Here is the link:
http://www.amsoil.com/lit/g2457.pdf
It takes just a moment to download.
Heath

Royal Purple is the most overpriced/under performing oil on the market.

I found the Valvoline 80/90 gear oil at Advance auto parts for about $5.00 a quart, it is the Durablend Synthetic oil, they did not have 75/90 so I am going to use this and see how good it is, I do not see any problems with using it.

Happy Thanksgiving everyone!

2007 Silverado 2500HD LT Ext Cab/Black Ext/Ebony Int/ LMM Diesel

Just changed my differential oil for the third time at 42,000 miles.

Have run 75w140 GM Synthetic oil for the first two changes at 2000 and 24,000 miles. The fluid I drained looked great and had very little metallic content. Magnetic drain plug looked great too.

Make sure you use a good synthetic fluid like GM, Mobil 1, Schaefer's or other brands.

i am going to add a mag hytec differential pan and wanted to know when i change the oil in the rear to i need to match the same kind/ viscosity/ thickness ect. up front? if not what is recomended for each.

O yea Heath i will be buying these products from you.
also what kind of Amsoil engine oil do you recomend and how much will i need?

THanks a lot,

EVan

It's up to you on what viscosity to run. If there is towing involved, I am recommending the 75W-110 for the rear. The 90 if fine for the front, but to keep from having to order two kinds, the 110 will be fine in front as well. That being said, the 90 is fine all around as well and will do a fine job. This is just my preference.
Just a reminder for those who may not be aware, the 110 viscosity range came out about 2 years ago. They took the 90 weight viscosity range and split it in half. The "thinner" or lower visc. end is the new 90 and the upper half is the 110. So the 110 is just an "old" 90 on the thicker end of the viscosity range.
For your 06, I would go with the AME(15W-40) for engine oil....10qt with filter. Not sure about quantity on the mag hytec. On many it doubles the amount but would need verfication on that.
Heath

Regarding the Mag-Hytec rear cover, I ended up putting in just shy of 7.5 quarts (the oil came right up to the first hash mark on the dip stick), and I went with the Amsoil SD 75w90 gear lube.

Yes, synthetic 75W-90 would be preferential/required/the only one you want in your hypoid drives/rear end. Every tractor trailer you pass on the intererstate is running 75W-90 and NOT a 140 weight gear oil... If 75W-90 provides adequate performance for an 80,000 pound truck, you are assurred of over the top performance in our applications.
George Morrison, STLE CLS