rear diffy fluid

[Camaro Dom]

so, i bought my car at 65k miles and now i'm at 112k. As far as i know, the guy never changed the diffy fluid, and i know i havent yet... i know the service interval on that fluid is like 90k. I have the y87 with 3.43's and limited slip...
is diffy fluid like trans fluid in that if its past the service interval you gotta just leave it in or should i change that stuff asap? I just dont wanna be buying a new rear end anytime soon... which is the best route to go?

[Firehawk N Wv]

Re: rear diffy fluid

I think you meant 3.42 gears. Probably just a typo. No since its never been changed Id go ahead and change the fluied. Ive never heard that about tranny fluid that if its never been changed then to leave it alone. I think the grade of rearend oil to use in our cars is 75w30 or it might be the other way around. I cnat remember exactly. I use Royal purple gear oil in my car along with their engine oil. I will be using their tranny fluid soon as I install my vig stall. The stuff is expensive but I think its well worth it if you got the money for it.

[D_Fisher]

Re: rear diffy fluid

Make sure your add the LSD additive too.

[vr4gasm]

Re: rear diffy fluid

75w90 is what i use by royal purple "max-gear" already has the limited slip additave in it

[Choppers]

Re: rear diffy fluid

how many quarts does it take?

[Firehawk N Wv]

Re: rear diffy fluid

I believe its 2 quarts.

[vr4gasm]

Re: rear diffy fluid

you will have to buy 2 but only use 1.75

[candela]

Re: rear diffy fluid

I have always used redline mtl and mt-90 in my cars. Was planning to use it in my maro this weekend, has anyone had any issues with it? I do not have the LSD, I have the middle gear ratio, 3.23?

[FirebirdGT]

Re: rear diffy fluid

https://www.amsoil.com/storefront/svg.aspx

https://www.amsoil.com/storefront/ada.aspx

Rear Axle (3.5 pints, 2 oz LSD additive)


I have a Zexel-Torsen LSD and use this.

.

[kala]

Re: rear diffy fluid

https://www.amsoil.com/storefront/svg.aspx

https://www.amsoil.com/storefront/ada.aspx

Rear Axle (3.5 pints, 2 oz LSD additive)

.

Today i was getting my oil changed at MGM lube (i.e. like jiffy lube). The guy on the counter asked me that if i ever had my diff fluid changed. I said to him that no. so, he checked something and told me he will change my fluid. I was concerned if i need synthetic (since i have y87) but he said that I don't. Well, I feel that i lost some HP. I was reading your write up in the tech section

The old disc-type limited slip differential (Auburn)was replaced with a Zexel-Torsen torque sensing limited slip differential in 1999. The new differential requires the use of synthetic differential fluid because of its design. The slip-limiting uses metal-to-metal contact inside the case and thus requires the use of the more "slippery" synthetic lubricant.

and realized that i don't need synthetic. Is this true?

Plan: I think he just replaced my diffy fluid with some cheap regular gear oil. so, i think i should change it. should i get this
http://www.royalpurple.com/prodsa/mgeara.html = 2 quart --- this saves me time because it's all in one

the one you referred, how do you mix it? it seems complicated. Let me know your thoughts. my car's in the sig.



:)

[HokieBird]

Re: rear diffy fluid

A synthetic is too slippery for an auburn. If you have an auburn you need some friction for the diff to lock. Hence, you put in the additive in your fluid.

[kala]

Re: rear diffy fluid

so, you're suggesting that i should buy some NORMAL gear oil and add this
https://www.amsoil.com/storefront/ada.aspx to the oil. it seems like my car doesn't pull like it used to after the diff. fluid change.i am not doing something right. i dont' want to drive too much with this fluid in the diff
Is there any way i can put the synthetic stuff??? like https://www.amsoil.com/storefront/svg.aspx or http://www.royalpurple.com/prodsa/mgeara.html
anyone else has any thought on this>>



:)

[kala]

Re: rear diffy fluid

A synthetic is too slippery for an auburn. If you have an auburn you need some friction for the diff to lock. Hence, you put in the additive in your fluid.

You are absolutely right .

This from the auburn website:

-IMPORTANT LUBRICANT NOTE
The Auburn Gear limited-slip differential design has been extensively tested with high quality non-synthetic 80W90 hypoid oils treated with GM or Ford friction additives (3 oz. of additive will treat 1 quart of oil). To avoid differential clutch chatter (noise) and for optimum performance, use the oil and additive described above. Use of other additive and oil types may cause differential clutch chatter.
GM Part Number: 1052358

Looks like i will be going to the chevy dealership tuesday morning. Atleast i know what i need now.

anyone know the diff. between hypoid and non hypoid oil? (just curious)



:)

[black98V6]

Re: rear diffy fluid

hypoid gear oil is designed for rear ends, it's because of the type of gear, straight cut gears can use non-hypoid oil, gears cut at an angle, like your trans and rear end gears need use a hypoid gear oil. This has to do with compression. Hypoid gear oil is designed to handle the greater pressure of the angle cut gears. all rear end oil will be hypoid.

Finally you shouldn't use those places to change gear oil or trans fluid as most of them use a pump to suck out the fluid. It's faster and less messy for them but you can't clean off the magnet on the inside of the cover which collects metal shavings.

[kala]

Re: rear diffy fluid

:tup: good info..

yeah those people i think sucked the fluid out because when my mechanic opened today, it was all gunky on the round pan. My mechanic did a very good job, cleaned everything and put it back. I used to leak a tiny bit fluid before but now it should be good. but anyway, job well done and thanks for your response.


:)