comatoastWS6

Going to do a drain and fill on the trans fluid and the diff.. Just wondering if there is a specific fluid/viscosity to use with either?


The rear diff is a must, as I dont think it has ever been changed ( currently at 115k miles ) Any particular fluid or additives I should be using?


The trans fluid looks descent, but I was going to change it anyways, so looking for fluid/additive suggestions there as well. Also would it be dumb to change the fluid now, before I put in a cooler? I MIGHT get 1000 miles out of it before it goes into storage but didn't know if I would lose a bunch of fluid during the cooler install

Only reason Im getting all maintenance up to date is because Im heading to the track this weekend to get some Baseline/stock runs before I start modding next spring and just want to make sure everything looks good. Especially in the rear end.. Maybe a little over cautious , but it cant hurt

demonspeed

iTrader: (7)

Torsen recommends synthetic 75-90 gear oil; no additive is necessary.

comatoastWS6

Thanks I saw ppl said either 75-90, or 80-90 was fine.. Just curious as some people said you had to add a (limited slip??) additive which the M1 and RP both have in it I believe..

This is the one I was looking at.

http://shop.advanceautoparts.com/p/m...ontent=7070039

RPM WS6

iTrader: (3)

The 80w90 conventional is for the '98 Auburn rear end. You also want to be absolutely sure to use the LSD additive with the Auburn. But you don't have a '98 so this doesn't apply to you.

75w90 synthetic is in fact recommended for use with the '99+ Torsen rear, as mentioned above. GM still recommends use of the LSD additive for the Torsen (per the owner's manual), but I'm not sure why. It's not really needed with that style of differential, but you can put it in if it makes you feel better.

For the trans, I'd stick with DexIII (something like Valvoline Dex/Merc is the closest you can get now, since specific DexIII licensing is no longer available). I wouldn't do a complete flush with that many miles on the trans unless it's always been changed regularly in the past. Junk getting pushed around during the flush and/or the chemical shock of 100% brand new fluid in a unit with that many miles on the original fluid has been known to cause issues for some people. I'd just do a pan drop, filter change and refill. You can do that 2-3 times over a period of time to get rid of a majority of the older fluid more slowly.

comatoastWS6

Thanks for the heads up... so would the oil I linked above be fine? Says it meets LSD requirements. I know its probably not as big if a deal as I'm making it. But just want to put good stuff in there.

Also should I use an OEM gasket or some type of gasket sealant.?

I planned on just doing a drain and fill on the trans fluid not a full flush. I'll just pick up a filter from the dealer and some sort of dexIII or similar.

RPM WS6

iTrader: (3)

I've never used aftermarket fluid or LSD additive in the Torsen or Auburn stock rears, only the GM stuff (GM makes both a synthetic 75w90 as well as a conventional 80w90, plus the LSD). Perhaps someone else can provide feedback on other brands of lube.

I've always used an OEM gasket for the rear. Some people like to use RTV type stuff though.

Any DexIII equivalent should be fine, I've just generally used Valvoline brand myself.

demonspeed

iTrader: (7)

Per Torsen: "GM issued a technical bulletin adding modifier to the rear axle oil. This was done to quiet what we call a "Rusty Screw" noise that we heard in a very small percentage of vehicles. This does not happen in all cases, however to address owner's concerns we asked that the modifier be used in all instances to insure that the driver would not get this noise. When replacing the fluid it is at the owner's discretion whether or not to add the modifier. Elimination of the modifier does not affect durability of the differential." SOURCE

I used to just go with a RTV or gasket sealant, but this last time I just could not get it to be leak free for the life of me. I finally installed a new cover gasket and all was well.

comatoastWS6

Thanks again guys. I can't pay... wont pay $40/qt for gm oil.. that's just crazy. We have amsoil and Mobil 1 ( my link from above ) local for $10/qt... I've been doing a little more reading and have seen a lot of people you use a synthetic 75w-90 WITH the gm LSD friction additive/ modifier have had the best results. I guess I'll try that first and if its still making noise , especially when tight turning I'll try the gm stuff in a few 1000 miles

RockinWs6

I would use the middle grade Amsoil severe gear 75-110 and use Dexron vi, the dex 6 works great and reduces clutch wear and slippage tremendously over the dex 3. Also is much better oil as its very stable over the long run and doesn't lose viscosity like the 3. I've used the dex 6 in 3 LS1 cars and it works perfectly, also good for 100k. I buy the dex 6 at walmart because ALL dex 6 comes out of the same pipe...............

demonspeed

iTrader: (7)

FWIW, I used Valvoline Synthamax 75-90 without adding the friction modifier.

comatoastWS6

Just curious. Is there really any difference between m1, amsoil, rp, or any other synthetic vs the gm 75w-90?

I did call another local dealer today and they have the gm diff oil for $27/ qt... amsoil is 12.99/ qt. And Mobil 1 is 10.99/qt

RockinWs6

The gm gear oil is Mobil 1 with grape scent<COMPLETE GARBAGE>

I would go with the Amsoil, nothing gets close to Amsoil in protection.

Royal Purple is a joke too, better than mobil 1 but you are buying their hype that's about it.

I've tested a few gear oils under hard conditions, Amsoil worked great, Valvoine was good too.

Mobil 1 failed miserably! Its also the factory fill on Ford F350 trucks>by 75k the rears are worn out if the oil wasn't changed out to something better.

How do I know all this you ask?




















FROM EXPERIENCE.

RPM WS6

iTrader: (3)

I've had no issues with the GM gear lube, be it conventional 80w90 or synthetic 75w90. Both have worked great for me, street or track.

Stan1911

I use Amsoil with 2oz of their slip lock additive on all my cars. According to Amsoil the slip lock is not needed, but it does not hurt to add a little.

bgw70

iTrader: (1)

New Transmission Filter, Fluid, Pan with Drain Plug and Rear End Lube

this maintenance was just performed on my 2000 T/A with 67k miles.
Valvoline MaxLife Dex/Merc ATF was used and a one gal jug is $17 at WalMart. The Specifications were checked on the Valvoline website to make sure it met all of the GM requirements. The AC Delco filter and gasket were purchased from rock auto and the items appeared to be made of quality materials. No RTV was used and no leaks have appeared. Soap and steel wool were used to clean up the pan! If you look at the pics in the other thread, you will see how nice the pan cleaned up!

The rear end service was performed last weekend, Valvoline full synthetic 75w-90, purchased at Advance, $10ea X2, quart bottles. The GM limited slip modifier was purchased on EBay for $8. Fel-Pro Gasket purchased from Rock Auto, no RTV and no leaks.

One last note, to ease the refill process, a Plews 55-001 pump was used and it was purchased on ebay for $8. It worked Great!
Also, the transmission and rear end are operating perfectly! I noticed a slight shifting difference with the transmission (crisper) but nothing with the rear end.
Hope this helps!

comatoastWS6

Thanks again everyone for all the help and advice. Ended up picking up 2 quarts of amsoil severe gear 75w-90 and a bottle of slip lock for $28, and a OEM gasket from the dealer for $9. So it was pretty easy on the wallet.

Next up is new trans fluid ( drain and fill ) filter and 24k cooler. Sad I'm getting all the maintenance up to date only to have to store it in about a month

RockinWs6

I 'd use the 75-110 Amsoil in your rear.