What diff fluid for my C6?
Thread Starter
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Joined: Feb 2014
Posts: 65
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From: Birmingham Alabama
What diff fluid for my C6?
Id like to change my diff fluid this week and I'm not going to pay 25 bucks per quart for the dexron LS 75w 90 from the dealership. At oriely they have oils ranging from 6 bucks per quart to 20. Some synthetic some not. What are you guys using, why and how well has it worked? Thanks!
Melting Slicks
Joined: Dec 2006
Posts: 2,694
Likes: 106
Buy the factory stuff man; it's the best, and you won't save much compared to other fluids when purchased thru a forum vendor (even with shipping). Bought mine from GM Parts House a while back, but all should have similar pricing. Good luck.
Instructor
Joined: Sep 2006
Posts: 233
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I have a 2007 that had SEVERE rear end chatter / clunk. I tried the dexron LS and it quieted it down just a little. It was still noisy and aggravating. Only 2,000 miles later I couldn't take it anymore. Based on other forum member recommendations i went with Amsoil Severe Gear 75/90 with an extra shot of slip additive. Rear end is dead quiet now. If i didn't have any problems i would have used the dexron product but it wasn't resolving the problem.
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Team Owner
Joined: Mar 2008
Posts: 21,502
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From: Southern Utah
Fair enough! Some on here have been changing diff oil at far less mileage. I had the diff fluid changed under warranty about 5 years ago because of the grinding noise when the car was cold and I was turning sharply to back out of my driveway. They did the new Dexron LS. Silence from then on, so I have to recommend it. But if yours is not presently grinding, then you might get away with something like the Mobil One diff 75w-90 but you will probably have to add some extra friction additive.
Thread Starter
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Joined: Feb 2014
Posts: 65
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From: Birmingham Alabama
Fair enough! Some on here have been changing diff oil at far less mileage. I had the diff fluid changed under warranty about 5 years ago because of the grinding noise when the car was cold and I was turning sharply to back out of my driveway. They did the new Dexron LS. Silence from then on, so I have to recommend it. But if yours is not presently grinding, then you might get away with something like the Mobil One diff 75w-90 but you will probably have to add some extra friction additive.
Team Owner
Joined: Jun 2005
Posts: 46,295
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From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
Let's face a couple of facts: the rear diff in the C6 HAS had issues, in the past. Most have either been corrected by owners' use of their own, aftermarket fluid, or by Chevrolet's fluid such that we really don't read much about it. EXCEPT when someone doesn't know, or had done the newer-service fluid from GM, or their own.
Please don't take this wrong, but cheaping out on fluid now may not be a good thing in the long run, or even the short run. If you ask me, your baseline is now: it runs, and it's not making any noises. BUT you have some miles on it, not a garage queen with 4K miles.
If it were me, I wouldn't use Mobil 1 even tho they're at least a co. with real engineers and labs (both plural) with an "engineered" product. Some fluid, most likely from GM, has been working in your car for 75K miles. That's what I'd go with, or one of the suggested companies from above posters. But note that JoeG most likely went with his aftermarket choice based on recommendations, and then switched out of it---and I think his usage would be considered "hard service" with 490 drag strip runs.
Please don't take this wrong, but cheaping out on fluid now may not be a good thing in the long run, or even the short run. If you ask me, your baseline is now: it runs, and it's not making any noises. BUT you have some miles on it, not a garage queen with 4K miles.
If it were me, I wouldn't use Mobil 1 even tho they're at least a co. with real engineers and labs (both plural) with an "engineered" product. Some fluid, most likely from GM, has been working in your car for 75K miles. That's what I'd go with, or one of the suggested companies from above posters. But note that JoeG most likely went with his aftermarket choice based on recommendations, and then switched out of it---and I think his usage would be considered "hard service" with 490 drag strip runs.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
AO Roads, you are correct. And if I recall correctly, Dennis50 who also uses his car hard had the same problem with aftermarket fill.
The diff doesn't hold much fluid so we are not talking about much money here. My recommendation is to stick to the factory fill based on experience.
The diff doesn't hold much fluid so we are not talking about much money here. My recommendation is to stick to the factory fill based on experience.
Race Director
Joined: Sep 2000
Posts: 11,142
Likes: 1,913
From: Missouri City, TX
I have used AMSOIL Severe Gear 75W90 in three vettes with outstanding results. Two of them had annoying slow speed turn chatter which was stopped with AMSOIL and the chatter has never returned. DEX LS is really good stuff but if you object to the price, AMSOIL is about half the price.
Drifting
Joined: Feb 2010
Posts: 1,527
Likes: 34
Road racing/auto crossing crowd expose to the harshest demands on every components on their car. With long sessions and week after weeks without a tear down. Here is one sample among many on what they say on oil:
http://forums.corvetteforum.com/auto...fferential+oil
http://forums.corvetteforum.com/auto...fferential+oil
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
Road racing/auto crossing crowd expose to the harshest demands on every components on their car. With long sessions and week after weeks without a tear down. Here is one sample among many on what they say on oil:
http://forums.corvetteforum.com/auto...fferential+oil
http://forums.corvetteforum.com/auto...fferential+oil
Another tidbit of info:
I installed a trans temp and a diff temp gauge in my car back when I did a lot of road course duty at HPDEs. My factory z51 trans cooler does a great job, never above 240 or so. But my car does not have the diff cooler that the z06 does and my diff fluid would get up to 280+ after 20 minutes, which would cause me to come off the track.
For serious track duty, a diff cooler is required like the z06 has.
For street and drag racing duty, it never gets above 240, and only up to that on extended highway runs. Around town or on the drag strip the needle never registers above 140 or wherever it starts to read (I don't recall exactly where that is).
Thread Starter
Advanced
Joined: Feb 2014
Posts: 65
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From: Birmingham Alabama
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.
