Differential Service

Jasonsupafly · January 2, 2012

2001 Z71 5.3 150k miles...My mechanic is servicing my transmission Wednesday for me. I would also like for him to change the rear differential fluid while hes at it .Can someone tell me what brand fluid would be best to pick up and how much to buy when I go to the parts store. Anything special or any kind of additive that is needed for this year truck? I would like to use a synthetic fluid in the differential. New gasket and fluid is all I need to pick up for this job?

fishbones182 · January 2, 2012

It should be 90w oil. Yes just a gasket and oil. I use synthetic oil in mine i cant remember how much i put in it though. Your owners manual should tell you the cpaicities on it though.

00Silverado4x4 · January 2, 2012

Should be just over 2 quarts. I just did mine a little while ago. The fluid mine calls for is 75w-90 synthetic. I ended up using synthetic blend due to availability. Do a search there a few threads out there. Good luck & happy reading!

Gurrzt · January 2, 2012

You should be using a synthetic 70w-90, and if your vehicle is equipped with the RPO code "G80" (locker), you will also need the 4 oz additive.

00Silverado4x4 · January 2, 2012

No additive required for the g80 in truck. Additive was required for limited slip units in cars.

txab · January 2, 2012

75w-90 with NO additive for a G80

Jasonsupafly · January 2, 2012

Thanks for the replies! Is this service pretty simple to do? Thinking about doing it myself to save a little money...

CapitalTruck · January 2, 2012

Easy as can be. It took me like .75 hours. Just take the fill plug off before you drain the fluid to make sure you can get it off. You don't want to drain it and not be able to refill it. On my 2004 there is no drain plug, you just take the cover off. If you've never done it before you better take the cover off and clean the magnet. It will be FULL of crap. 75w90 synthetic is factory requirement. You'll have no problems. When you fill it up, the full like is .6-1.6 inches below the fill plug. Just grab an allen wrench that is about 1 inch long and fill it up to where when you stick the top of the allen wrench in the fill hole the oil level touches it. It took like 2 1/10 quarts.

Jasonsupafly · January 3, 2012

Thank you!

Jasonsupafly · January 3, 2012

Is Mobil 1 LS okay to use or does it have that additive in it already? Kindof hard to tell by the way they have it worded on their site...or what would be the best brand to use?

Ryan00TJ · January 3, 2012

Is Mobil 1 LS okay to use or does it have that additive in it already? Kindof hard to tell by the way they have it worded on their site...or what would be the best brand to use?

I use the M1 Syn 75W-90LS in mine with no problems. Eaton Auto locker runs like a swiss car.......

CapitalTruck · January 11, 2012

I used Valvoline SynPower 75w90. I'm sure Mobil 1 would work fine.

jaredthomas27 · January 11, 2012

Just be prepared to scrape the crap out of your dif cover edges to get the old gasket off. It might be wise to have a good sharp scraper or something like that on hand incase its hard to get the old gasket off. That is what I had to do. And yes Mobile1 75w-90 LS is good w/o the additive. Should be a little over 2 qts. Also, it makes it easier to fill up if you remove the spare tire, or just use a pump. And if you have a 4x4 go ahead and change the front dif fluid and transfer case fluid if you havent done that in a while. Happy working!

mathewsmatt · January 11, 2012

my son and I are abut to service his differentials on his 1994 z71 and we have used and have been recommended using Lucas brand differential lubricants.

they are usually $10 a quart and all depending on what differential you have which all chevy's are pretty close in capacities as fra as I'm concerned and to service the front and rear diff. (unless 2wd) you should need 3 quarts max since when we did his before we bought 3 quarts and that was just the right amount for the front and rear diff.

Lucas costs more but its well worth it and its not like your changing it as often as your oil so it definitely pays for itself.

peteking · January 11, 2012

Just be prepared to scrape the crap out of your dif cover edges to get the old gasket off. It might be wise to have a good sharp scraper or something like that on hand incase its hard to get the old gasket off. That is what I had to do. And yes Mobile1 75w-90 LS is good w/o the additive. Should be a little over 2 qts. Also, it makes it easier to fill up if you remove the spare tire, or just use a pump. And if you have a 4x4 go ahead and change the front dif fluid and transfer case fluid if you havent done that in a while. Happy working!

+1. Exactly what I experienced. The job took just under an hour....but half of that was spent scraping off the old @#$%# gasket in pieces with a razor scraper. That chore sucked. I filled with Mobil 1 75w-90 and have been very happy with it.