What diff fluid for my C6?
Team Owner
Joined: Jun 2005
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From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
Although I don't have a C6, I do use the below in my C5 Z06 at the track and have sold it to many forum members who report good results (no chatter). As mentioned above, though I can't quote pricing online, even with shipping this aftermarket option is well under what it would cost for the Dexron LS at the dealership:
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT)
AMSOIL Slip-Lock Differential Additive (Product Code ADATB)
More than happy to get AMSOIL products for forum members at dealer wholesale pricing, about 25% below retail, via the AMSOIL Preferred Customer Program. Drop me a PM if interested.
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT)
AMSOIL Slip-Lock Differential Additive (Product Code ADATB)
More than happy to get AMSOIL products 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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AMSOIL Dealer (Forum Vendor)
AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
C66 Racing #66 NASA ST2, SCCA T2
AMSOIL Dealer (Forum Vendor)
AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
Advanced
Joined: Dec 2012
Posts: 52
Likes: 4
I am currently using Mobil 1 LS and have changed it twice to make sure most of the old stuff (Royal Purple) is out. The Royal Purple lasted about 10,000 miles and did a pretty good job for the first 5,000 miles. Mobil 1 is not any better than the original factory fill (2007) initially, and seems worse after 7,000 miles.
Burning Brakes
Joined: Jun 2009
Posts: 1,135
Likes: 226
From: Roanoke Indiana
I am currently using Mobil 1 LS and have changed it twice to make sure most of the old stuff (Royal Purple) is out. The Royal Purple lasted about 10,000 miles and did a pretty good job for the first 5,000 miles. Mobil 1 is not any better than the original factory fill (2007) initially, and seems worse after 7,000 miles.
Pro
Joined: Oct 2003
Posts: 558
Likes: 0
From: Draper UT
Hope this is on-topic:
2009 Z06, street use only -
Called three local dealerships in Mesa, AZ - they both recommend the following for the differential:
Synthetic Gear Lube 75W90 GM# 88900401
PLUS
Limited Slip Additive (4oz) GM# 88900330
I thought we were using GM LS 75W90 without additive?
Any thoughts?
2009 Z06, street use only -
Called three local dealerships in Mesa, AZ - they both recommend the following for the differential:
Synthetic Gear Lube 75W90 GM# 88900401
PLUS
Limited Slip Additive (4oz) GM# 88900330
I thought we were using GM LS 75W90 without additive?
Any thoughts?
Burning Brakes
Joined: Jun 2009
Posts: 1,135
Likes: 226
From: Roanoke Indiana
Hope this is on-topic:
2009 Z06, street use only -
Called three local dealerships in Mesa, AZ - they both recommend the following for the differential:
Synthetic Gear Lube 75W90 GM# 88900401
PLUS
Limited Slip Additive (4oz) GM# 88900330
I thought we were using GM LS 75W90 without additive?
Any thoughts?
2009 Z06, street use only -
Called three local dealerships in Mesa, AZ - they both recommend the following for the differential:
Synthetic Gear Lube 75W90 GM# 88900401
PLUS
Limited Slip Additive (4oz) GM# 88900330
I thought we were using GM LS 75W90 without additive?
Any thoughts?
"As of January 2008, the oil specified for use in the Corvette differential is Dextron LS Gear Oil 75W-90, part #88862624 (#88862625 in Canada). No additive is required or recommended – just add straight Dextron LS 75W-90 only"
http://www.southerncarparts.com/corv...nge-pm-43.html
Last edited by 1972bluelt1; Apr 5, 2014 at 05:23 PM.
Burning Brakes
Joined: Jun 2009
Posts: 1,135
Likes: 226
From: Roanoke Indiana
I am currently using Mobil 1 LS and have changed it twice to make sure most of the old stuff (Royal Purple) is out. The Royal Purple lasted about 10,000 miles and did a pretty good job for the first 5,000 miles. Mobil 1 is not any better than the original factory fill (2007) initially, and seems worse after 7,000 miles.
http://www.mobiloil.com/USA-English/...Corvettes.aspx
If you add additional friction modifier, how much? can you use too much?
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Race Director
Joined: Sep 2000
Posts: 11,142
Likes: 1,913
From: Missouri City, TX
Thanks for all of the responses guys. I think I'm going to go with the stock fluid. I found it at gmpartsdirect for $13.70 a quart. The local dealership wants $25 and change for the same thing 
. Besides I'm not knowledgeable enough to figure out if I need friction modifier or not with whatever aftermarket oil I might have chosen.
. Besides I'm not knowledgeable enough to figure out if I need friction modifier or not with whatever aftermarket oil I might have chosen.
Safety Car
Joined: May 2011
Posts: 3,807
Likes: 508
From: Oshawa, Ontario
$12.
$12. at local GM dealer for Dexron LS p/n 88862624 per quart. I also now use it in my Dodge Ram as their gear oil is $35. per quart.never an issue in the Corvette or Ram.NEVER ADD friction modifier to it!if changeing yourself by hand with hose on bottle buy 3 quarts.difficult to squeeze all oil out of container.get a longer hose to install on container
Last edited by irok; Apr 7, 2014 at 11:57 AM.
Melting Slicks
Joined: Aug 2000
Posts: 2,327
Likes: 44
From: Sacramento CA
Drifting
Joined: Mar 2011
Posts: 1,448
Likes: 56
From: Bath NC
I have used Royal Purple, Amzoil, and GM LS diff oil. In my opinion, Amzoil is the best, Gm LS is definitely good, Royal Purple, There's too much snake oil magic going on for me. I wasn't happy with the feel.
This was true between the Amzoil and the royal purple in the outdrives of my high performance boat as well.
This was true between the Amzoil and the royal purple in the outdrives of my high performance boat as well.