Billiumss

iTrader: (11)

I have about 13,500 miles on my 2001 Camaro SS M6 and I want to change the rear end fluid.

What should I use regular or synthetic? Royal Purple? I need a GM additive, correct?

Whats the best way to get the new fluid in the rear end? Any write-ups out there?

I've done a few head and cam swaps on my car but never messed with my rear end yet, I figured this is the best place to ask.

Any tips or suggestions are greatly appreaciated.

Bill

Predator

If you have the Torsen, which you probably do (it came stock), just use synthetic 75W90. If an Auburn, use petroleum based and GM additive. Install University has a writeup about changing the stock cover, and refilling the fluid.

Ryan02SS

iTrader: (3)

I have the Torsen LSD in mine. I use Mobil 1 Synthetic 75W-90 w/o any additive. M1 is blended with the additive allready in the mix. However if you would notice chattering from the rear add a small amount of the additive until the noise subsides. I've never had a problem with straight M1. Make sure the gasket mating surfaces are clean. I run lacquer thinnner over the surface before applying RTV to clean any impurities off the surface. It's a PIA to fill our rear diffs from the location of the fill hole. With the typical qt jug of gear oil its hard to squeeze more than 3/4 of a qt into the diff. I now use an electric oil pump that's awesome! No mess or problems. Simply turn it on and it pumps oil into the diff. Throw a pan underneath, when it starts running out the fill hole turn the pump off and tighten plug. Simple as that. Any of your local auto stores should have them for about $20. They come in handy for diff jobs, refilling your T56, etc...... HTH

tici

iTrader: (1)

how about 75-140 GL6 oil?
I have some noise during decel from 50 to 30, will this help?

Ryan02SS

iTrader: (3)

Many companies recommend 75W140 for towing or severe service operations. The thicker oil should provide more "cushion" for the pinion teeth and ring teeth under high load levels or stress situations. Drawbacks could be nothing to maybe a slight loss of MPG or power. We're talking 1hp here at max. I frequently use 75W-140 in my Wrangler's front differential to mask the ratcheting sound of the locker that resides there. It does not totally mask the sound but reduces it noticeably over 75W-90.

[/QUOTE] I have some noise during decel from 50 to 30, will this help? [QUOTE]

It can only help the sound.

tici

iTrader: (1)

It wines a little during decel when the engine isn't braking the car. I mean: when there is just a little pressure on the coast side of the ring gear. This happens in 6th or 5th during decel. If at that moment I shift to 4th the pinion puts a little more pressure to the ring gear and the noise stops. Mechanically it's not a problem, I just don't like it.
Acceleration or keep the speed is absolutely quite.

Shuld I give it a try to the thicker oil?

Billiumss

iTrader: (11)

I just have the Torsen.

So would you say Mobil 1 Synthetic and Royal Purple are the same?

Can you have too much additive?

Predator

No additive needed with a Torsen. The additive is for the clutch-like disks in the Auburn and Eaton type of posi. The Torsen uses a gear type of system.

I'm sure M1 and RP are not exactly the same, additives and so forth, but they'll both probably work fine. Your choice.

keliente

iTrader: (22)

You don't need synthetic in a torsen. Regular 80w90 is fine.

Predator

Either works.

bshell

iTrader: (24)

I have the Auburn diff in my car and access to Redline 75W90 syn. Would I be better off with non-synthetic and GM additive?

keliente

iTrader: (22)

It is going to perform the exact same way.

My main point was that there is no sense in paying a lot of money for synthetic oil for stock 10 bolts. People go a little nuts with it when the only time you would need it is if you were doing some kind of road racing, sustaining speeds of 150mph or so for hours at a time...otherwise your gear oil is not going to be overheating during street/strip use....

Just my .02.

gwj

keliente,
What is your opinion on using 85w140(Lucas) ? Just overkill, or no harm done?
Also, if the LS additive is not needed for torsens, why does the
owners manual state otherwise? Asking your opinion, as you
seem to have excellent knowledge/skills.(read your gear write up)
gwj

joecar

If you read the various car mags. you will find tests showing synth. gear oil netting a few extra hp.

99PontTA

i use M1 75-90......its a huge step up from reg 80-90 gear oil.The car is definatly more responsive with the M1 in the rear.

bad6as

iTrader: (17)

eather works fine keliente said.

i dunno about you guys but i havent found and good brands of standard 75w90 at any of my local auto parts stores.

but i know jiffy lube charges $30 to suck out the old fluid and full it back up with the standard 75w90. good deal imo

but i use synthetic in my 98

keliente

iTrader: (22)

The manuals are pretty much the same for all camaros, no matter the trim level/options/etc. They are pretty generalized so that everyone can use them...that's most likely why they specify you need the rear end additive, because some of the cars will have Auburns. The auburns have clutches in them that need the additive, the torsen works in a different way. For argument's sake, I have a torsen...on two different occasions I changed the rear end fluid, one time using additive, one time not. It makes no difference.

In my opinion 85w140 would be a little overkill, shouldn't be anything wrong with sticking with the normal weight lube for a 10 bolt.

keliente

iTrader: (22)

It's arguable. It's pretty difficult to compare dyno graphs when you are only looking for a difference of 1-2hp or so...because really you could gain or lose 1-2hp depending on how much time you are letting the car sit in between runs. Just my .02.

joecar

The guys at CC, HR, CHP, GMHTP are pretty savvy and I recall that they saw more than just 1-2 HP increase and were shooting for consistency.

Edit: I seem to recall that they got 8 HP increase.

Granted, on the street, the differential will not see temperatures seen in road racing;
however, with the hypoid gear arrangement, the ring and pinion gear teeth do scrub sideways over each other, so if you can reduce friction by using synth. gear oil you will increase the life of the ring and pinion, for only $9 versus $4.

It's probably the cheapest non-free mod.

keliente

iTrader: (22)

I'm not so sure that syn fluid is that much different than regular fluid as far as lubrication...after all people ride on stock rear ends for 100k+ miles on regular fluid without issue. Our own formula has 142,000 miles on the rear end, and has only ever received non-syn fluid. When I removed the guts of the rear end to install 3.73s, they looked perfect.