Going to change out the diff fluid this weekend and reading through the old treads its was personal preference. Seems like most people not using GM are using AMSOIL. Give me some tips on what to buy or not to buy.

I have a 2004 with the original diff still quiet as a tomb... I use Redline. Swapped out the OE fluid @ 8K mi.
http://www.redlineoil.com/

I have a 2004 with the original diff still quiet as a tomb... I use Redline. Swapped out the OE fluid @ 8K mi.
http://www.redlineoil.com/

I noticed that name a couple of times as well. Are you using the synthetic and what weight?

i'm getting ready to throw royal purple in mine at the end of the week.

RP 75w90 then switched to 75w140 for kicks. Still a little purr around 50 mph but most passengers don't know the difference. 75w @ 12K miles, now have 31K total miles. Switched to 140 about 1500 miles ago. Three road course days and all is well. Cheap insurance for $20. :)


Norm

see i started with the rp 75-140 and still could hear the whine but then i changed to rp 85-140 and is soild and quite as a rock so far so good 2000mi

good info in this thread since i'm ready to replace mine

see i started with the rp 75-140 and still could hear the whine but then i changed to rp 85-140 and is soild and quite as a rock so far so good 2000mi

Do you drive it in the colder weather? I don't think I would ever be out when its under freezing plus we dont get that cold up her in the northwest.

Good news!


Norm


see i started with the rp 75-140 and still could hear the whine but then i changed to rp 85-140 and is soild and quite as a rock so far so good 2000mi

I've been changing diff with RP at every engine oil change when I was tracking car, I figure there's alot of Hp going through 1.5 qts. Recently have had to put friction modifier to stop chatter even though it says it has it in it. Otherwise happy with RP.

Original diff with tracked maggied car..

I just bought Amsoil, a couple of hours ago.

Been using the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (http://www.c66racing-synthetics.com/Product%20Bulletins/SVGPB.htm) in my 02 Corvette Z06 track car since 2004 without any diff failures in something like 30 races and about a dozen or so driver's ed type weekends. Put the same fluid in my 06 CTS-V last year and have been very happy with it.

I do not use extra additive with this fluid as it already has friction modifier in it and neither of my car's diff's chatters. I did the diff seal recall about a month ago and they changed the fluid to GM fluid and my car's diff chattered driving it off the lot. I suspect, but don't know, that they left out the additive (which the GM fluid requires). I changed to AMSOIL, did a bunch of figure 8s and it was quiet for a day or so, then I experienced some chatter. I was going to add some additive, but by the weekend, the chatter had stopped and it hasn't come back. I suspect it took a few more tight turns than I expected to work the new fluid into the clutch packs.

Without trying to start a fluid war, some will find this AMSOIL sponsored gear lube test interesting. Both Red Line and Royal Purple were included.
AMSOIL Gear Lube “White Paper” (http://www.amsoil.com/lit/g2457.pdf) (2 MB pdf file)
:cheers:

FYI, I would NOT recommend putting in Mobil 1. I added it,m and it has caused my plutch packs to grind on low speed turns. This is with the GM friction modifier added for good measure.

-Chris

AMSOil without the friction modifier in my Diff and no whine.

I run AMSOIL with no noise, but I never heard any from the GM stuff either.

I just bought Amsoil, a couple of hours ago.

I run AMSOIL also....

What weight are you guys using for the AMSOIL? I live in Indiana. It will be sitting in winter.

75W 90 Severe gear in mine but I'm in CA.

Looks like the next fluid change in my diff will be by the dealer tomorrow.

I drive mine all year around. We'll see a couple of weeks worth of 20F and a few nights in the single digits. Currently running 75/140 and probably go back to 75/90 for winter.

Norm

RedLine works for me...

Just changed my new differential @ 6,200 miles last weekend. Used GM synthetic with additive at $24/qt wholesale. Old fluid I drained looked fine. There was a little buildup of what looked like break-in grease on the plug - but that was it.

how hard is it to change the rear end diff fluid? what do i need to do?

Its easy to change. You need a 10mm allen socket and a drain pan. Filling it up is what sux. I recommend getting a suction gun to fill it up with. I did it with a tube attached to the bottle of rear end lube but it was messy. I believe there are instructions in the FAQ. Next time I will use the suction gun and be done in 10 minutes no mess. I used Royal Purple.

Having dealer service diff tomorrow while in for other warranty items... I bought a couple qts of RP 75/90 that I'll have them put in... currently experiencing some whine, so I'll reply afterwards

-shannon

Having dealer service diff tomorrow while in for other warranty items... I bought a couple qts of RP 75/90 that I'll have them put in... currently experiencing some whine, so I'll reply afterwards

-shannon

I had some whine when I changed mine. It didn't quiet it down any. I am currently trying to get the dealer to replace my diff.

Its easy to change. You need a 10mm allen socket and a drain pan. Filling it up is what sux. I recommend getting a suction gun to fill it up with. I did it with a tube attached to the bottle of rear end lube but it was messy. I believe there are instructions in the FAQ. Next time I will use the suction gun and be done in 10 minutes no mess. I used Royal Purple.


Suction gun is the only way to go. I did my rear with a pump, but after doing the tranny with the gun I won't go back.

Jon

What ever you do don't use that Royal purple Syncro Mesh in the trannsmission. AmsOil in mine now, what a difference, Shifts like it should.

I've used RedLine Trans Fluids in my Jeeps (I think it was like MTL-90 or something like that) and it makes a huge improvement in the way it shifts....very easy on the syncros. Never tried their gear lube in the diff. I may do that since it's alot easier to get ahold of than Amsoil. How often are you guys changing your diff fluid? Every 5k?

I suggest getting a socket with the 10mm allen head attachment on it. MUCH easier to get up into the fill bolt. I have B&B 3" exhaust and couldn't get my hands in there with the regular allen wrench. Drain plug, no problem.

Anyone try Redline Shock Proof?

I have though about putting in some shock proof light wieght when my car finally get shipped up here. It is a 75 140. I have a bunch in my shop for my race car. It does mention that it is for dog ring gear boxes and that is all I have used it in.

Having dealer service diff tomorrow while in for other warranty items... I bought a couple qts of RP 75/90 that I'll have them put in... currently experiencing some whine, so I'll reply afterwards

-shannon

Which dealer- Carter? I need some work done too, are they friendly to a modded car?

BTW- your car looks really low, what did you use?

Thanks- sorry I stole the jump the other day, bad habit sometimes.

Which dealer- Carter? I need some work done too, are they friendly to a modded car?

BTW- your car looks really low, what did you use?

Thanks- sorry I stole the jump the other day, bad habit sometimes.

Hey man what up???? Yeah you go the jump alright... then I felt like a chump trying to catch up... :thepan:

Yeah, I went to Ron Cartier (that's kart-ee-yay) to have the stuff done... all I can say is that be sure they know ALL of the items you need done ahead of time... oh, and Brian, service writer, said they're backed up like 2 weeks! They may try to tell you that GM won't warranty certain items if that's what you're taking it in for.

BTW - the RP diff fluid has given me a little more confidence in the ass end of my V... no whine whatsoever :thumbsup:

Hey Guys,

Just picked up a 2004 V and am very happy with it!!! I have been pouring over this forum for the last little bit and tons of great info.

So my question is....I'm getting ready to change out the diff fluid and have read that this stuff is pretty good..
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90.

How many quarts do I require?

Thanks in advance

Jeff

Pick up 4 quarts. There will be some left over.

I am in Florida. What Amsoil would I use in the diff and trans? 4 quarts for the diff and how much for the trans?

4 quarts? I thought it was 1.5?

Did everyone use ramps or jacks and stands? I was planning on accomplishing this feat tomorrow.

2 quarts is right. I was thinking of the trans.

Transmission (4.0 qt)
Diff (2.0qt) you wont use all of it. Just fill untill it runs out the fill port

It's more like 1.25 quarts. I did mine on ramps and used Amsoil. I would say use anything but change it often. I had some nasty stuff on that plug after only 750 miles on a new rear diff.

Use ramps....easiest way to go. I went GM Fluid in the new diff and it was whining...switched to Redline 75w90 and now it's pretty quiet!! I'm loving that stuff......they make good trans fluid too.

what amsoil do u use in the trany

AMSOil ATF for the trans. There is a gear oil atf mix that is supposed to work best. if your interested, do a search.

I used the Severe Gear in the Diff with the GM friction modifier. She is quiet after 17K so I'm happy.

FYI, I would NOT recommend putting in Mobil 1. I added it,m and it has caused my plutch packs to grind on low speed turns. This is with the GM friction modifier added for good measure.

-Chris

FYI,

I switched back to OEM fluid, and no more binding on tight turns. Damned, mobil1.

-Chris

I replaced the stock OEM fluid with the same and haven't had any problems at all. The only disadvantage in using the stock GM fluid is the price. The advantage is that GM might deny a claim if the replacement fluid in the differential does not have the distinctive "grape" smell when they do their warranty investigation - so why take a chance?

Hahahha that "distinctive" Grape smell doesn't smell like Grapes! You can be dumb like me and take a whiff.....I'm sure the engineers are :histeric: over that one

I replaced the stock OEM fluid with the same and haven't had any problems at all. The only disadvantage in using the stock GM fluid is the price. The advantage is that GM might deny a claim if the replacement fluid in the differential does not have the distinctive "grape" smell when they do their warranty investigation - so why take a chance?
I was a little concerned with the warranty so I taiked with the Service Manager and he told me the AMSOil with the GM friction modifier was a good combination. When I asked him if they would void the warranty with the AMSOil instead of the regular fluid and he told "not at this dealership". He told me that it would be hard to tell the GM stuff from the AMSOil when it's used anyways.

I'm liking this dealership so far.

I was a little concerned with the warranty so I taiked with the Service Manager and he told me the AMSOil with the GM friction modifier was a good combination. When I asked him if they would void the warranty with the AMSOil instead of the regular fluid and he told "not at this dealership". He told me that it would be hard to tell the GM stuff from the AMSOil when it's used anyways.

I'm liking this dealership so far.

What one dealer says isn't necessarily what all would say but AMSOil is probably the best of the lot if you believe their "independent" overall quality test data. GM comes in a close second. I would be a little hesitant using anything else unless you were getting monetary kickbacks.

Regarding the use of tracers, including smell, to tell if you were using different lube, the most telling story will be if you have fluid that is visibly degraded in color or flow characteristics due to extreme operating conditions. In that case they might send the fluid in for chemical analysis (if there's any left along with the exploded rear-end) to support or refute the claim.

I am in no way affliated with AMSOil and I understand what your saying. I am in no way saying that one should go out and use this fluid, I am just posting what I do use.

Everyone needs to make their own descision and if your even moderately worried about being denied a claim then I would recommend sticking with the recommended fluid.

With all of that said I would recommend changing the fluid more often then recommended by GM for 2 reasons. When I changed the fluid in mine there was a lot of the clutch material on the plug. If this gets into the gears it will probably accelerate wear. Second is it's not that expensive and it's easy to do with the right tools.

I think if GM wants to find a reason to deny a claim they will and if not the fluid I'm sure they will find something else.

Everyone needs to make their own descision and if your even moderately worried about being denied a claim then I would recommend sticking with the recommended fluid.



I am going with every other oil change.

I do about 5K which is close to every other.

I changed my new diff fluid at ~6K and found very little contamination on the drain plug. Unless I track the car in the future, I doubt I will change it again for quite some time. The whole reason for using a quality lube is to have confidence it will stand up to moderate demands over time. If I found some evidence of component wear related contamination I would change it sooner.

I saw the most wear on the first change and of course it was the GM recommended fluid. I figured this should be expected because the clutch packs are breaking in and a little extra on the first change was normal. If you had very little wear it sounds like you got one of the better diff's.

I had a new diff put in 10,000 mi ago and cahnged to RP after 1500 mi. There was no audible difference, still some whine. I just changed to the Amsoil severe gear a couple weeks ago and no noise so far, just crappy Falken 452 road noise.