View Full Version : diff. fluid change
awacki007
11-14-2005, 08:40 PM
i was reading on past posts, and someone mentioned an additive for the locking differential. what kind of additive and for what pupose? thanks...and also should i change diff. fluid and txfer case fluid with the first oil change?...thanks again
From what I understand, if you have a locking differential (G80), you need to use SAE 80W-90 GL5 Gear Lubricant, GM P/N 1052271. Do not use limited slip additive. I'm pretty sure that the locker is made by Eaton. A call to your local service writer / shop would give you a definitive answer.
bmm354
11-14-2005, 10:07 PM
Another option is Amsoil synthetic. According to the company no additional additives are needed.
I changed out the rear diff. fluid for Amsoil this past spring and it's been great so far. With the old lube still in there the diff had started rumbling/chattering (I have the G80 limited-slip) after interstate driving. After the fluid change that went away completely. I didn't add any additives and it hasn't given me any trouble. I even drove in some tight circles after the fluid change just to make sure nothing was binding, and it was fine. The limited-slip function still works fine too.
LAVABOY
11-15-2005, 12:48 AM
:) I changed to amsol in my diff's, runs great!:D I'm not a mech but a lot of posts I have read says that the fluid from the factory is Junk in the diff's. No additives required. :D
Good Luck to all LAVABOY:cool:
ScarabEpic22
11-15-2005, 02:10 AM
I run complete Amsoil too!! I have the G80 limited slip w/3.73 gears, switched this past summer with 50k to Amsoil 75W-90 Severe Gear Lube, no additives required (you can put their additive in if your diff. is chattering after the new fluid, but I didnt need to) Never had a problem.
2002BlkLTZ
11-15-2005, 12:54 PM
Erik what is the capacity, if you know of hand, of the front and rear diffs? Never mind, looked it up. Looks like 6.6 pints for both 4 rear and 2.6 front.
tblazed
11-15-2005, 01:35 PM
I changed my rear diff with G80 to Royal Purple Max Gear 75W-90 a year ago. $8 or so a qt. at NAPA. Prior to doing that, I had emailed Amsoil, Royal Purple, and Red Line. Only RP would put in writing that their oil meets and exceeds the GM spec. (Amsoil said theirs should, but would not say it actually did meet GM spec.) Results were, oil seepage I was getting at the pinion shaft seal and dripping onto the sway bar completely stopped, no more leak, and differential operates smooth as silk.
zamar
11-15-2005, 01:39 PM
Erik what is the capacity, if you know of hand, of the front and rear diffs? Never mind, looked it up. Looks like 6.6 pints for both 4 rear and 2.6 front.
Front should be 4 pints and rear 2.6 ;)
2002BlkLTZ
11-15-2005, 02:43 PM
In that case, my owner's manual, as well as the .PDF manual Here (https://www.mygmlink.com/pdf/go2content/manual/US/en/chevrolet/2002trailblazer.pdf) are incorrect. If it doesn't go to the correct section, click on section 7 in the table of contents, then scroll back one page to the end of section six.
zamar
11-15-2005, 03:19 PM
In that case, my owner's manual, as well as the .PDF manual Here (https://www.mygmlink.com/pdf/go2content/manual/US/en/chevrolet/2002trailblazer.pdf) are incorrect. If it doesn't go to the correct section, click on section 7 in the table of contents, then scroll back one page to the end of section six.
Thats odd. My Chiltons has it as I stated earlier. My mind doesn't function very well until about 2:00pm (nightshift slug). Either way you will need 2 quarts per axle.
You only need the additive if you have an aftermarket LSD, like an Eaton Posi, instead of the stock G80.
tblazed
11-15-2005, 04:43 PM
We have lockers in ours anyway so the limited slip additive is pretty much a moot point. Unlike a limited slip, normally the clutch pack in a locker stays disengaged. Only time the clutch pack is engaged is when the difference in RPM between the axles is great enough to make a mechanical spring loaded pawl in the differential spin out from centrifugal force and lock the axles and the clutch pack together. So, since it is normally disengaged, it doesn't have to slip the clutch pack going around a corner like a conventional limited slip and should never chatter. I am sure I will get corrected if my description is wrong!
Also FWIW, on my 2002 and a friend's 2003, the rear axle and differential are manufactured by American Axle, not Eaton. Their logo ("AAM") is cast into the diff housing.
I had about 4 oz left of the two quarts of oil I put in the rear dif., filled until oil was just starting to dribble out the filler hole. 2WD here so that was it for me.
Also FWIW, on my 2002 and a friend's 2003, the rear axle and differential are manufactured by American Axle, not Eaton. Their logo ("AAM") is cast into the diff housing.
No doubt that the axle/diff is AAM, yet I'm sure that the locker itself is an Eaton Corp. Product. It was in my neighbors 2003 LT, and it is in MY 2005 LS. Like I posted, a call to your service writer or parts dept. will confim that. :m2:
tblazed
11-15-2005, 06:20 PM
I figured since it's an AAM axle assembly it probably has something like this inside...
http://www.aam.com/technology/tech_prod_dl_diff.html#TRLK
EDIT: BUT...! I remember now...! ran this down last December in an email to American Axle that I just re-read, that Eaton does supply the G80 differential unit.
AFAIK, if your vehicle has G80 as an RPO code in the glove box, then it has the Eaton Gov-Lock.
ScarabEpic22
11-15-2005, 10:55 PM
We have lockers in ours anyway so the limited slip additive is pretty much a moot point. Unlike a limited slip, normally the clutch pack in a locker stays disengaged. Only time the clutch pack is engaged is when the difference in RPM between the axles is great enough to make a mechanical spring loaded pawl in the differential spin out from centrifugal force and lock the axles and the clutch pack together. So, since it is normally disengaged, it doesn't have to slip the clutch pack going around a corner like a conventional limited slip and should never chatter. I am sure I will get corrected if my description is wrong!
Also FWIW, on my 2002 and a friend's 2003, the rear axle and differential are manufactured by American Axle, not Eaton. Their logo ("AAM") is cast into the diff housing.
I had about 4 oz left of the two quarts of oil I put in the rear dif., filled until oil was just starting to dribble out the filler hole. 2WD here so that was it for me.
I had about that much left over after I filled my rear diff, but if I remember right, the amount in my Haynes manual stated the capacitites wrong. I think it took about 1-2qts in the front and the same in the rear. I bought 3 (or 4) qts and it took all but 8oz between the front and rear diffs (G80 rear).
awacki007
11-16-2005, 07:48 AM
thanks guys for all your input
2002BlkLTZ
11-16-2005, 12:22 PM
The diff's on our trucks take quarts, not pints, as indicated in the owners/chilton's manuals? Interesting. I think I may go with the Royal Purple I know a couple of gear heads who use it in all of their vehicles.
tblazed
11-16-2005, 02:44 PM
Some interesting video clips about Royal Purple...
http://www.royalpurple.com/video/video.html
the roadie
11-16-2005, 04:08 PM
No doubt that the axle/diff is AAM, yet I'm sure that the locker itself is an Eaton Corp. Product. It was in my neighbors 2003 LT, and it is in MY 2005 LS. Like I posted, a call to your service writer or parts dept. will confim that. :m2:
Eaton has a nice web page and animation on the unit:
http://www.automotive.eaton.com/product/traction_stability/lockingdiff.html
http://www.automotive.eaton.com/images/products/systems/lockingdiff.jpg
What I'd really like is the electronically controlled one:
http://www.traction.eaton.com/prod1.htm
Then you don't have to wait for the initial tire spin for it to lock up, since you might be mocked by the Jeeps with manual lockers who don't spin at all.