Differential Oil Replacement
#1
Racer
Thread Starter
Differential Oil Replacement
Hello Fellow Vetteheads,
While replacing tank etc checked the oil in the differential and noticed it to be very black...how does one get it out ..should it be warm?..what oil and additive do I use to replace?
Thank You in Advance.
While replacing tank etc checked the oil in the differential and noticed it to be very black...how does one get it out ..should it be warm?..what oil and additive do I use to replace?
Thank You in Advance.
#3
Burning Brakes
Member Since: Mar 2012
Location: Belle River Ontario
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2015 C3 of Year Finalist
I just picked up a fluid transfer pump to do mine.
Princess auto 14 bucks
You should use genuine GM differential fluid and make sure to pick up a small posi additive as well.
Take the car for a short drive to warm up the fluid first, makes it easier to get it all out .
When I did mine I put the new fluid in a pail of hot water before opening them up to make putting in the new lube much easier
Good luck.
Princess auto 14 bucks
You should use genuine GM differential fluid and make sure to pick up a small posi additive as well.
Take the car for a short drive to warm up the fluid first, makes it easier to get it all out .
When I did mine I put the new fluid in a pail of hot water before opening them up to make putting in the new lube much easier
Good luck.
#4
Le Mans Master
I'd be careful with the friction modifier additive. It's function is to allow more posi clutch plate slippage around tight turns, to help quiet things down. Problem is, stuff sometimes takes away a good amount straight line posi clutch pack lock up action, when you're really wanting it. Never use it myself. You can always add it later.
#5
Melting Slicks
I'd be careful with the friction modifier additive. It's function is to allow more posi clutch plate slippage around tight turns, to help quiet things down. Problem is, stuff sometimes takes away a good amount straight line posi clutch pack lock up action, when you're really wanting it. Never use it myself. You can always add it later.
Use of the POSI additive is strongly recommended. 1 bottle per change.
#6
Burning Brakes
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Even do yourself a favor and do a "search" on this forum regarding differential fluid changes and you will see for yourself that the addition of a 4oz bottle of posi fluid is reccommended in virtually every post.
#7
Race Director
For the last 10 years I have used Amsoil 80W-90. It has the friction modifiers in it. Absolutely zero issues with no additive and the posi works fine.
#9
Le Mans Master
75W-90 Mobil 1 synthetic with no friction modifier for 22 years now with zero issues. From my experience and others who have chimed in here and many times when this issue has come up in the past with fluid for the differential, it strongly appears that the friction modifier is NOT needed with synthetic gear oil. All of the fluids for these cars are so much better than 30-40 years ago with the advent of synthetic fluids that following the manufacturer recommendations from that era seems a little archaic, IMHO. Whatever you choose to do will work as long as there is nothing wrong with the diff.
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Primoz (05-08-2018)
#10
Premium Supporting Vendor
AMSOIL Synthetic Gear Lube SAE 80w90 (Product Code AGLQT)
More than happy to the above for forum members at dealer wholesale pricing, about 25% below retail, via the AMSOIL Preferred Customer Program. Drop me a PM if interested.
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C66 Racing #66 NASA ST2, SCCA T2
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AMSOIL Ordering Information (Retail sales using reference #1206638 benefit the forum.)
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C66 Racing #66 NASA ST2, SCCA T2
AMSOIL Dealer (Forum Vendor)
AMSOIL Ordering Information (Retail sales using reference #1206638 benefit the forum.)
AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
AMSOIL Catalog
#12
Le Mans Master
As mentioned, you can always add stuff later, but not so easy taking it back out. My C6 ZO6 has a pretty noisy rear posi diff around tight turns, getting many owners to add the GM friction modifier. Really doesn't bother me, as road track the car, wanting all the perfomance advantage possible. Car came from the factory this way, and really not one to second guess the GM engineers.
#13
Le Mans Master
I just changed rear end fluid today. You will need a device to suck the old fluid out. Also a device to put the new fluid in. I used a small pump that screws on to the gear oil bottles. I attached a clear hose to the pump so that I could see the fluid going in. Pump the fluid in until it starts to dribble out of the plug opening. I dropped my spare tire to give me better access to the fill plug. Everything should be easily available at your local auto parts store. By the way I used Amsoil synthetic Severe Duty Gear oil AND the Amsoil Limited Slip additive.
#15
Burning Brakes
I've done this job a few times, using different options re oil.
I now have rebuilt the diff and have gone back to teh tried and tested, and in my opion best option - GM oil and GM additive. I've found it works best, and lasts longer between changes.
For you guys in the US, obtaining it is easy. More difficult for us here in Europe, but worth the hassle as far as I'm concerned!
I now have rebuilt the diff and have gone back to teh tried and tested, and in my opion best option - GM oil and GM additive. I've found it works best, and lasts longer between changes.
For you guys in the US, obtaining it is easy. More difficult for us here in Europe, but worth the hassle as far as I'm concerned!
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spitzbar (10-19-2023)
#16
Another place to put the drain plug is under the bracket that holds the strut rods. Drill and tap 1/4" NPT just far enough to one side that you miss the ring gear. Make the hole on the bracket larger, of course, so you can easily insert/remove the plug..
#17
Le Mans Master
I read somewhere that the models with aluminum housings were better left without a drilled and tapped drain plug. '80-'82s I believe. The housings tend to strip out when tightening a drain plug. Just some additional info to digest.
#18
Had a 1976 L-82, 4-sp
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Here is what 63mako uses:
AMSOIL Synthetic Gear Lube SAE 80w90 (Product Code AGLQT)
AMSOIL Synthetic Gear Lube SAE 80w90 (Product Code AGLQT)
#20
Racer
Thread Starter
What are the correct names for the GM oil products for:
Manual Transmission
Differential
Additive
Thanks
Manual Transmission
Differential
Additive
Thanks
Last edited by Bond007; 05-14-2012 at 10:23 PM.