differential Fluid recomendation

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Jan 19, 2010 | 02:36 PM

Rollin

Thread Starter

Instructor

Joined: Oct 2007

Posts: 194

Likes: 0

From: Mesa Arizona

differential Fluid recomendation

OK I've been searching and reading for a couple hours. Decided to just come out and ask.
I'm wanting to chhange out my Differential fluid. I thought it would be easy but it sounds like there are a lot of opinions on what to use.
What is the latest and greatest on the best differential fluid to use? How much do I need to buy. And if its a mix what are the amounts of each. I have a 2002 C5 with 68k. The last thing I want to do is mess something up by using the wrong product. Any help here guys?
THANKS

Jan 19, 2010 | 03:06 PM

Bills03Coupe

Drifting

Joined: Apr 2004

Posts: 1,886

Likes: 20

From: Olathe, Kansas

Quote:

Originally Posted by Rollin

I changed mine out about a year ago. I used the Redline 75w-90 with the friction additive already in it. I did not have to add any additional.
additive. I used a little less then 2 quarts. One tip, remove the fill plug first, to make sure you can get it out! I've heard of instances where guys have drained the differential and could not get the fill plug out to refill it! My differential was chattering like crazy on low speed turns, after this change it's completely quiet. Very easy to do, just drain, reinstall the drain plug, then add fluid until it runs out of the fill hole (You'll need a pump to pump the oil into the differential) reinstall the fill plug and you're done!

Jan 19, 2010 | 03:38 PM

Glennm27

Race Director

Joined: Jan 2002

Posts: 19,557

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From: I love you & miss you Linda

2017 C7 of the Year Finalist

St. Jude Contributor

Royal Purple Max Gear No additional additives needed.

Jan 19, 2010 | 03:39 PM

bucwheat

Race Director

Joined: Oct 2007

Posts: 14,108

Likes: 26

From: 4th on the list of top 100 in USA Ga.

I just changed mine to Royal Purple.

Jan 19, 2010 | 04:38 PM

BenC5

Drifting

Joined: Feb 2009

Posts: 1,379

Likes: 1

From: MA

I also went with the Royal Purple as it has a good reputation on this site, especially when I didn't have to add any friction modifier with it.

So far it has been working well.

I really like that I can go to my local Pep Boys and buy it.

Jan 19, 2010 | 04:51 PM

itzza427

Le Mans Master

Joined: Sep 2007

Posts: 7,604

Likes: 8

From: Belleville Il

Another satisfied Royal Purple guy here,,,trans and differential!!

Jan 19, 2010 | 04:53 PM

ALLEGRO

Le Mans Master

Joined: Feb 2003

Posts: 6,682

Likes: 144

From: Memphis Tennessee

I am going to go with Mobil 1 "LS" this summer. I don't believe I will need the additive either.......

Jan 19, 2010 | 05:48 PM

Double G

Pro

Joined: Sep 2007

Posts: 547

Likes: 2

From: Clinton Twp. Michigan

Dte

I know that DTE only recommends Redline.

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Jan 19, 2010 | 05:48 PM

c5blkvetteguy

Burning Brakes

Joined: Oct 2008

Posts: 1,062

Likes: 2

From: Minnesota City MN

I use the GM stuff that is used in the C6. Gene Culley hooked me up. It has the friction modifiers in it. Just pour and go. Get two quarts, that easy.

Jan 19, 2010 | 06:00 PM

#10

rpm462

Melting Slicks

Joined: Mar 2006

Posts: 2,997

Likes: 36

From: Ocean Springs MS

Quote:

Originally Posted by bucwheat

I just changed mine to Royal Purple.

Same here.

Jan 19, 2010 | 06:11 PM

#11

J S Machine

Race Director

Joined: Feb 2008

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From: Maker of Sharp Objects, AL - Roll Tide

St. Jude Donor '10-'11-'12-'13-'14-'15-'16-'17

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Quote:

Originally Posted by Glennm27

Royal Purple Max Gear No additional additives needed.

Can't go wrong with Royal Purple. If you have a manual trans, RP in there is good too

Jan 19, 2010 | 06:58 PM

#12

seamus2154

Drifting

Joined: Nov 2008

Posts: 1,450

Likes: 140

From: Palm Beach Florida

I have used Amsoil sever gear 75/90w for years on all my vettes. The best. Also has some addative in the formula so most times you don't need to add posi fluid.

Jan 20, 2010 | 09:26 AM

#13

Rollin

Thread Starter

Instructor

Joined: Oct 2007

Posts: 194

Likes: 0

From: Mesa Arizona

I have to thank you all. It seems Royal Purple wins hands down if number of posts count. Looks like I know what I'm doing this weekend. Since it's due to rain all weekend I'll have no reason to put it off. I'll try to remember to follow up in a couple months and voice my opinion. Thanks

Jan 20, 2010 | 09:42 AM

#14

Glennm27

Race Director

Joined: Jan 2002

Posts: 19,557

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From: I love you & miss you Linda

2017 C7 of the Year Finalist

St. Jude Contributor

Quote:

Originally Posted by Rollin

Beware, in your garage this can be a little messy and the old fluid smells bad.

Jan 23, 2010 | 10:18 AM

#15

C66 Racing

Premium Supporting Vendor

Joined: Aug 2001

Posts: 5,364

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From: King George VA

For those wanting to make an informed decision about gear lubes, this is a good read. Even though this is obviously an AMSOIL commssioned study, you'll learn valuable info on all the other choices out there even if you totally discount the AMSOIL.
AMSOIL Gear Lube “White Paper” (2 MB pdf file)

__________________

C66 Racing #66 NASA ST2, SCCA T2
AMSOIL Dealer (Forum Vendor)
AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)

Jan 23, 2010 | 01:59 PM

#16

IRON MAIDEN

Melting Slicks

Joined: Aug 2009

Posts: 2,785

Likes: 8

From: Sacramento California

Gear oil seems to be an easy choice. Tranny fluid is a different story. I'm still unsure what to use as I have a 97' 6 speed with I assume paper blockers.

Jan 23, 2010 | 02:50 PM

#17

Carcass

Drifting

Joined: Feb 2007

Posts: 1,793

Likes: 7

From: Santa Maria Ca.

Quote:

Originally Posted by IRON MAIDEN

Gear oil seems to be an easy choice. Tranny fluid is a different story. I'm still unsure what to use as I have a 97' 6 speed with I assume paper blockers.

I used Mobil 1 in the tranny on my 98 for about a year,and while i didn't HURT anything,it didn't help the shifting,either-almost as if it's a little too "slippery" to let the synchros do their thing.
About 2 months ago,I decided to try "the cheap stuff"-Valvoline Dex/Merc.
It made a world of difference-the tranny shifts like a new one now,easy into first and reverse,no "notchy" shifts into ANY gear.
I figured it's like an hour to change it,so I could always try something else if it didn't work out(or declare the tranny a POS and start planning for a rebuild),but it actually took care of it.
I used Mobil 1 LS in the diff,only because the parts store was out of Royal Purple on the day I did the job,it's quality stuff,so I'm sure it'll be fine.

Jan 23, 2010 | 03:36 PM

#18

KOZ

Drifting

Joined: Jul 2006

Posts: 1,284

Likes: 59

From: Somewhere out there

If I use AMSOIL 75W90 how do I know if I need to add the LS modifier fluid?

Jan 23, 2010 | 07:35 PM

#19

dobewillie

Race Director

Joined: Mar 2006

Posts: 10,477

Likes: 4

From: lockport n.y

This Spring I will try the Royal Purple

Jan 24, 2010 | 09:33 AM

#20

C66 Racing

Premium Supporting Vendor

Joined: Aug 2001

Posts: 5,364

Likes: 38

From: King George VA

Quote:

Originally Posted by KOZ

If I use AMSOIL 75W90 how do I know if I need to add the LS modifier fluid?

The AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT) comes with friction modifier already in it. I use this fluid in my 02 Z06 and used it in my recently sold 06 CTS-V without additional modifier and neither diff chattered. Diff chatter is caused by the clutch plates in the diff chattering vice sliding across each other when one wheel turns at a different rate than the other (like in a hard corner in a driveway, parking lot). This can be heard and sounds just like a chatter. The C6 guys have different clutch plates and this is a real problem with them and most need extra AMSOIL Slip-Lock Differential Additive (Product Code ADATB). C5s don't seem to have the same issue. The downside to just adding extra additive up front is that you somewhat defeat the purpose of a limited slip diff. If the clutch plates slip too much you are getting less torque to the wheel with grip, thus less performance. For C5s, I do not recommend adding extra additive unless you experience chatter, and the vast majority do not for fluids such as the AMSOIL Severe Gear that have the friction modifier already in it.

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