I thought the Amsoil was around $15 and the Dexron is more like $26, but that's a dealer price...vendors here have it for less....but it requires buying 3 bottles because it takes a little more than two quarts.

 

^^Personally, Amsoil is an hyped up and overpriced multi level marketing scheme - beside their synthetic engine oil is a mixing of types.

Most of the currently available "Full Synthetic" motor oil is a blend and not a true synthetic. bobistheoilguy on the web is a place to get educated.

Redline is 100% synthetic. With no blending to be "Full Synthetic" or mixing of types.

Bottom line: if you want to use synthetic or better put, 100% synthetic and not some "Blend" or "Mixed Type" - Redline.

I get all my "no hype" 100% synthetic Redline products from Amazon - Free Shipping even to my door in Hawaii.

 

Not sure why you would imply a mixing of different basestocks is a bad thing. Top tier oils (of which not many exist in the U.S. since the NAD authorized Group III to be labeled as synthetic here) have been blending Group IV PAO and Group V Polyol Esters for decades. Adding a small amount of Group V Polyol Ester to a predominantly Group IV PAO basestock lowers the fluids coefficient of friction and balances out the two basestocks opposite effect on porous materials like seals.

Without trying to start an oil war, this data would indicate AMSOIL is more than a hyped up and overpriced MLM:
AMSOIL Performance Test: A Study of SAE 5w30 Synthetic Motor Oil

You can dispute this test, but oil companies in general aggressively self police advertising claims via the FCC. Other oil companies do not take AMSOIL's performance tests to task with the FCC.

For the OP, I've been using the Severe Gear 75w90 in my 02 Z06 at the track since 2004.
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT)
AMSOIL Slip-Lock Differential Additive (Product Code ADATB)

The Severe Gear does come with friction modifier and most cars (C5 Corvette included) do not need extra additive to prevent diff chatter. The C6 diff is different and uses different clutch plates than the C5 and prior Vettes. These are much more prone to diff chatter and most use at least a few ounce more of additive to prevent the chatter.

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.

 

^^^I do understand that you sell the product.

But personally:

-First, I don't buy into the claim while One Group "Swell" seal and adding the other Group "Shrink" the same seal - sort of the Push & Pull effect?

-Second. My red flag went up - especially after looking into pricing on the prefer customer and dealer wholesale pricing gimmick. I even went so far from being just a customer, then joined up as a preferred customer to "take advantage of the 25% off retail" and moved up to become a dealer. Took another serious look, and asked the common question: "even if I am not into the business, trying to profit and just use the product for myself. I've got nothing to lose - Right?". Then checked into the whole complexity of dealing with shipping & cost to one control business here in Hawaii so as to share shipping. I promptly cancelled the membership.

---

Never have associated seal problem with 100% Redline Synthetic. Reasonable priced for 100% synthetic no gimmick stock + Amazon Free Shipping to my door.

 

The amsoil is $15/qt and the dexron is $14-$17 online.

I actually picked up 2 qts and the additive this afternoon from a distributor 5 miles from my house, but thank you!!

Every single person i spoke to, or chatted with online that uses amsoil severe gear oil in the diff raves about the performance. I didn't come up with one negative.... Redline is good as well, but what turned me off to them was a test i saw online that said the redline failed at high temps....

 

Amsoil

 

I use both brands just in different cars. Redline saved my other car from selling it 20 years ago. The MTL made shifting the manual like slicing cake. Using the factory fluid made shifting very difficult along with grinding and it just wouldn't go into gear.

 

You may very well be right. All I'm going by is personal experience. I swapped fluid on my ZO6 from factory to royal Purple. Wow that was a bad mistake. Couldn't believe it was that hard to shift. Switched it out to Amsoil the next day and it was sooo much better. Just my story and I'm sticking to it. I own no stock in amsoil

 

That is correct. All of their Severe Gear and I think also their standard diff fluids all include the additive. That is standard advice from AMSOIL: Add slip lock additive if chattering is still present. Severe chattering as I was experiencing with my 06Z needed that extra & separate dose of additive. Prior to the introduction of DEXRON LS for MY2009, GM had a TSB advising dealers to solve a customer's chattering problem first with a Mr Goodwrench fluid change followed by 2x the normal addition of slip lock additive. If that didn't resolve the problem, then GM would authorize clutch pack replacement. At that point in time since AMSOIL, Redline, RP, etc already included slip lock additive, Forum members recommended that a 1x separate dose of slip lock additive be added to a DIY change with those premium aftermarket fluids. With the Z06s larger fluid capacity, I added 6 oz of the AMSOIL slip lock additive to the Severe Gear fluid change. After the figure 8s done in a parking lot, the chattering was forever banished from my car.

 

"Every single person i spoke to, or chatted with online that uses amsoil severe gear oil in the diff raves about the performance. I didn't come up with one negative.... Redline is good as well, but what turned me off to them was a test i saw online that said the redline failed at high temps...."

My intention is not to start an oil war. But where was that online test you referring to? Curious!

There was one in bobistheoilguy.com. Which pointed out that multi level marketing oil company did not compare apple with apple - which is what most company out to make $ do - by doing test to their favor - in this case, a bench test to simulate real world to boot. In all fairness, however - that online thread was in regards to motor oil. Nonetheless, tactics like that really underscore my confidence of a company.

In terms of gear oil, which involves the shear factor - in which case, hard to deny superior capability of 100% synthetic to combat shear between transmission gears. Can not speak for anyone else, my Redline has proven its worth in my '05's trans and diff.

 

In my DTE built differential I use Redline 75/140 as recommended by DTE.

I asked how they came to this recommendation and was told that it has worked the best for them.

Understand that they do mods within the diff concerning clutch pack material and oiling improvements among other things.

How this relates to using the heavier oil I do not know.

 

Understand and respect your position on AMSOIL. But to share information on the seal impacts, try googling "polyol ester impact on seals" and look for independent information.

This is from an article on bobistheoilguy:
" In automotive applications, the first qualified synthetic crankcase motor oils were based entirely on ester formulations and these products were quite successful when properly formulated. Esters have given way to PAOs in this application due to PAOs lower cost and their formulating similarities to mineral oil. Nevertheless, esters are often used in combination with PAOs in full synthetic motor oils in order to balance the effect on seals, solubilize additives, reduce volatility, and improve energy efficiency through higher lubricity. The percentage of ester used can vary anywhere from 5 to 25% depending upon the desired properties and the type of ester employed."

PAO (Group IV basestock) and polyol ester (Group V) basestock are totally different compounds. It does not surprise me that their impact on porous material like seals is different and that by blending them you'd get a mix of the impacts.

 

In my past life, I've dealt with many sub driver and crew - and come away with an impression that they have a common trait - tolerant and sociable. My exchanges here have prove that again.

I thank you for your informative inputs and being tolerant with me.

Mahalo.

 

ok, so I did the diff change tonight and went with amsoil severe gear 75w-90 and the amsoil additive. Many people said, "you only have 28k miles on an '06 no need to change the diff fluid for a while." We'll, I am SOOO glad i did it. What came out of the diff was BAD! The smell was the normal old diff oil smell but the color and consistency was incredibly dark brown and watery, not oil like at all! The consistency was somewhere towards the low end of water and how thick the oil should be when new. (so i say below mid way of the 2) and the color was close to black. After the change i did the normal circles and figure 8's then went on a little ride without WOT. Feels nice but not too much of a noticeable difference, but i'm glad i did it! Thanks for all you input guys, and no matter if you use RP, amsoil, redline or the dexrol ls, CHANGE THAT DIFF OIL!!! Now I know my tranny fluid needs changing cause i'm sure it's bad too, but i'll have to take that somewhere i think.....

PS I was surprised on how much oil it took. I only put in about 1 3/4 quarts plus the 4oz additive when it started seeping out.... I thought i didn't put enough in and did something wrong, but when i put the old oil back in the empty amsoil bottles, it was only 1 quart and about 23oz out of 32, so i think i did it right....

 

 

You got the right amount back in. You buy 2 qts for a standard vette diff but the actual refill amount is more like 1-3/4 qts. Same is true for the Z diff with cooler and circ pump. Buy 3 qts but the refill will be more like 2-3/4 qts.

 

cool.

 

GM has upgraded their differential fluid to LS Gear Lube, part # 88862624, which says on the bottle that is contains the limited slip friction modifier.
I just changed the fluid on my 2004 Z06, and just stayed with the GM fluid.
The factory fluid has been in there for 40,000 miles and was surprisingly clean when I drained it.
I never had a chattering problem with the original GM fluid, so hopefully, the new fluid will be as good or better.