My '03 Z06 used to grind between 4th and 5th gear shifts, plus it was difficult to get it into 5th. Under warranty, the dealer put in GM Synchromesh; this did not fix the problem. Based on my past cars (3 Mazda RX-7's), I used Mobil1 gear lube. So, I had the Synchromesh drained and put in Mobil1 ATF. I have had not one grinding noise since the change to Mobil1. In the past, I have tried various gear oils (not ATF) for my transmissions---I have found that Mobil1 provides me with the smoothest shifts among all of the brands that I have tried (AMSOIL, Castrol, and Redline).

 

Used Redline In Trans.will Use Red Line In Diff.car Shifts Much Smoother With Red Line,hope Diff.will Be The Same-smooth!!!!

 

DTE, have you tested Red Line "Heavy Shockproof" lube yet? Or the other two lighter Shockproof lubes? Do you think they might be an improvement over the Red Line 80W140 as Red Line suggests in their Tech article?

Thanks, Curt

 

Man, I have stock fluid in trans and diff, 02 Z06, 427 stroker making around 580 RWHP. Haven't had any probs but after reading all this I want to chage both fluids soon! How many quarts do the read end and trans hold?

 

Actually, I think it is quite the opposite. Exxon Mobil can afford to pay hundreds of thousands of lawsuits and still remain profitable, where smaller companies like Amsoil and Royal Purple could easily be bankrupted by thousands of lawsuits. When it comes right down to it, Amsoil and Royal Purple have a more vested interest in making a trouble free product.

 

1.89 quarts, I believe.

 

I am planning on giving my 2002 Z06 the Royal Purple treatment for all of the fluids. I will see how it does.

 

Probably because GM found it saves 0.05 MPG with the lighter oil in the differential.

 

The 6MN is 4.1 qts. The differential is 1.6 qts. plus what ever 4 oz (the friction modifer) is.

 

You guys & gals can use whatever you like. I have a DTE diff - I use what Phil of DTE tells me to use. Hasn't failed me at ~600rwhp....

 

Maybe, maybe not....



This is your car right now, yes?

Oh -- here's a picture of mine. I use the standard GM recommended diff oil -- it gets me where I'm going, and looks good along the way:

 

I see you trying to make more friends...

EG's pic just shows me that he is working on it.. Does not mean the Tranny Failed..

Some peeps like to mod their cars and drive em harder than GM planned for..
And YES there actually are people who can redesign a part better than the Original GM part.. Why? Because the re-engineered part had a different purpose in mind than GM originally intended..not becuse they are SMARTER than GM..

Not everything GM designs is for OUR benefit.. Take the output shaft on the differential.. GM is not stupid... They Know it breaks under a hard load. They left the Dog Bone design in it for a reason...So it will continue to break! and they hope it breaks AFTER the warranty.

No engineer is that stupid to see a failure that has a cheap and easy fix and does not implement it.. unless there is an alterior motive..Your Pocket book...

All these "Little" upgrades can be offered by GM for nothing more than a few $100 bucks to the bottom line.. Bet there is not one Vette Owner who'd balk at the price increase.. But GM won't anything that increases the life of the parts steals from their Dealers Service Bottom line.. Keep that in perspective.. Yes... it is a big conspiracy..

 

I see the PMs are flying today, chuckster, nice of you to check in on this thread as well.

The gentleman who started this thread has a 2003 coupe, which may still be under warranty, base or maybe even extended GMPP.

So, why would he want to use a fluid that would void that warranty, or why would anyone recommend something other than what fits his particular application (as opposed to yours).

The problem with quite a few of the "good advice" posts is that people don't tailor their advice to the question asked, but what they would like to have heard.

England Green has had plenty of problems with his car (www.grond.tv), and the shape that it's in shows that radical advice may not always be the best advice.

If this thread had been about someone looking for diff fluids for a highly modified, highly stressed, non-warrantied car, dragster, then yes, use all the Marvel Mystery Oil you want.

But, it's a stock car, with a warranty, and should be treated as such.

Cheers! See you again soon, I'm sure.

 

PM's???? How can you see my PM's?

You are making a gross assumption that putting a Different Fluid in the car is going to cause a catostrophic failure.. Remember GM is not GOD.

They don't always recommend things for the same reasons the user needs.

And now to on to the Original Poster Question..
Differential Fluid, which do you use?

If he was interested in the GM Fluid I am sure he would not have bothered posting in the C5 Tech. That being said he asked for clarification to understand the differences. Which is exactly what he got. Nobody is BASHING the GM recommendation.. They are simply saying there is better..

Again.. GM most likely uses theirs to maintain the Fuel Economy. I highly doubt it's for longevity. If that were the case Race Engines would use 5w10.. Not 50W...

Just pointing out that GM does NOT have a perfect track record with engineering.. SO why do people always bring up the fact that GM has more engineers and more money to spend on Research and development.. So TRUST THEM... I guess nobody else could design a better column lock securty system. Or Fuel Sending Unit. Maybe they needed to spend a few more dollars on those...

How about those C6 Z06 Differentials Breaking? And not even at the track... Let's all trust GM's Fine Engineering and Testing... Guess what... I bet anyone who installs a hardened output shaft just violated their warranty... Even though they just made it better..

 

I see that you have been studying "How to win friends and influence people"

1> I have not had any problems with my car that I did not personally cause.

2> My car is (or rather was) at ~600rwhp. As a FYI - stock is 280-300rwhp

3> I hate when stock owners poke their noses into that which they have no clue.

4> I have never had a differential failure. No gear whine, no noise, nothing. Worked perfectly at my power level. And worked perfectly under all conditions and loads.

5> I have no need to PM anyone. Anyone can see a fool with their own two eyes - no need to draw attention to them.

6> Nothing in the quote from the thread starter (above) about "I have a stock car under warranty" - unless, of course, my old eyes are failing me....

7> becomes you.... You did such a good job in the NorthEast section that I see you decided to branch out...

 

I have and so far so good...no problem tranny A4 shifts so smooth with the tune until I was asked did I have a shift kit in it.

 

So let me get this right - EG works on his car and knows what he's talking about, and you don't work on your car very much, therefore probably don't? Fair enough.

Fact of the matter is, there's much better stuff out there than what GM puts in a bottle.

Also, I have a feeling DT puts a shorter warranty on their differential for TWO primary reasons: 1) their pocket books are NOT as deep as GM (nor is their profit margin on what they sell) and 2) their products are sold to people who will be abusing to a much higher degree, on average, than stock GM parts.

 

Last night I changed my fluids in transmission and differential to Royal Purple products. I read for a year all the posting...and finally decided it was my turn. Two noticeable differences: shifting was smoother but made the stock shifter feel sloppy and the rear end is quieter. Now I want a new shifter.

 

Actually, I think it's the opposite of your statement. Considering that GM. Chyrslyer, Porsche, etc. use Mobil1 as both the factory fill and the recommended oil, as well as the fact that Mobil1 meets/exceeds the manufacturer's specs, neither ExxonMobil or the car manufacturers are likely to use an inferior product that would result in warranty claims and law suits. I am sure that the smaller oil companies could have you tied up in court for several years in order that you can prove that it was their product that caused an engine failure. The burden of proof would be on you and would be very difficult to prove; the smaller oil companies do not have money to give out to every complaintant. Amsoil and RP do not have a more vested interest in making a trouble free product...that is your opionion, not based on fact. Also, ExxonMobil makes their own product and has continually improved their oils and gasoline products, just as ChevronTexaco has made continous improvements (Techroline to Techron; regular coolant to Dex-Cool). When BMW first started having carbon buildup issues they could not figure out what the problem was. Mercedes, on the other hand, did not have carbon build up issues. To make it short, when Mercedes test drove their cars, they would fill up at the Exxon station near the factory...Exxon had an effective additive package, way before its time.

 

On my C4 I had a racing expert shop rebuild my diff. He put in new factory clutch packs and assembeled it as I watched. It was built "right and tight". We put in Redline diff lube (I don't recall which one). After 3 autocross weekends it was slipping like crazy. We rebuilt it again and used the factory lube and it was fine for the next 4 seasons and was still tight when I sold the car.... Yes, I know a D44 isn't quite the same thing as we have in our cars now, but it works pretty much the same way.

The lesson here is that once a LSD unit starts to slip you get a lot of wear, and things go south in a hurry. I like to hear a bit of graunching or complaining from the rear end in slow tight corneres, that means to me that it is still tight...

If you are a street only driver and just want to cruise or polish, then put anything in there that keeps it quiet. If you are serious about performance and want it to last you don't want a lot of lubrication between the clutches, you want it to grip and stay tight. For that reason I've stayed away from the "super lubes" and kept the factory fill in the diff. I'm finishing my second season of serious (two drivers) of autocrossing with my Z and the diff is still tight....