so while today I removed my rear end crossmember , i have to get a different transmission jack as the one i have won't work..but any ways
for the Differential fluid i am looking at buying the amsoil severe gear 75w-90 ( two quarts) and reading a bit on the forum i have noticed that member Torque on his website said he added some amsoil -slip lock Differential additive which most are saying is not needed? any truth to that?
thanks Ryan

 

Changed mine a month ago using Amsoil without the additive and no problem noticed. Around 1,000 mi since change.

Thanks Toque for your great website. Got the Amsoil thru C66racing.

 

Year ago and no issues...

 

Did you do the figure eights in the parking lot to pack the lube in the difference?

 

I did. Also used the Slip-Lock additive...not knowing that it wasn't necessary... No issues so far...but I'm not even 300 miles into the new fluid. Not worried though.

IMO...you should be fine with the Amsoil Severe Gear only. Do the figure-8's and all should be fine. Follow Toque's procedure...easy stuff.

 

I use Amsoil for everything except my oil (only because my car has only had Mobil 1 in it since the day it was new). I used the additive in mine and haven't had an issue yet. The Torque drive transmission fluid realllly smoothed up my shifts too. I used Toques website too for the recommendations and procedures.

 

No additive here either using Amsoil Severe Gear. About 3,500 miles and no issues however I do not race.

Might as well change the trans fluid while your there if you have a MN6 with Amsoil Torque Drive.

 

Yes.

 

Ryan,
The AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT) comes with friction modifier already in it and adding extra is not normally needed to prevent diff chatter in the C5. Having too much additive will not harm the diff, but may cause the diff clutch plates to slip more than design. The spec for the C5 diff is 75 lb-ft. This may lower with too much additive and thus you will lose some performance where the extra few lb-ft of torque matter (track, drag strip, etc). I advise forum members not to get the extra additive for the C5. Toque opted to add extra additive.

Note that the above discussion is not applicable to the C6. For the C6 diff, GM changed the diff clutch plate material and pressure. This caused most C6 diff's to chatter and resulted in numerous TSBs. Finally after several years GM came out with a new diff fluid (Dexron LS) which has lots of additive. Most C6 owners that use the Severe Gear do add at least a few ounces of the AMSOIL Slip-Lock Differential Additive (Product Code ADATB)

More than happy to get AMSOIL products for forum members at dealer wholesale pricing, about 25% below retail, via the AMSOIL Preferred Customer Program. Drop me a PM if interested.

 

thank you c66 racing..that is what I was looking for, so now I know what fluids to put in my car..i am pretty much sold on the amsoil product..its great stuff!

Ryan

 

Happy to help.

 

SubDriver says you don't need to add the ADDITIVE.
I did just as a precaution.
I did numerous figure "8's" in a parking lot to work the fluid into the rear end clutch packs.

Knock on wood, its been perfect for a couple years since changing the rear end fluids.

Toque

 

GM has upgraded their differential fluid to LS Gear Oil, part #88862624, which says on the bottle that it "contains the limited slip friction modifier".
I have read that other forum members have had chattering problems until they went back to the GM fluid.

 

That is really only applicable to the C6, not the C5 which is the subject of this thread.

GM changed the design of the diff clutch plates from the C5 to the C6; they use different material and have a higher compression pressure. As a result, when the C6 came out there were numerous complaints of diff chatter. GM released several TSBs on the issue and finally corrected the diff chatter problem with the "new" Dexron LS (really has been out for about 5-6 years now). Dexron LS has much more additive than most fluids to deal with the behavior of the C6 diff clutch plates.

For older diffs like the C5, the amount of additive most aftermarket fluids, including the AMSOIL Severe Gear mentioned above, is sufficient to prevent diff chatter. For the C6, though the Severe Gear does have additive already in it, most add extra additive to effectively bring the additive level up to match that of the Dexron LS.

While the Dexron LS does have the right additive level for the C6 diff, it is probably more than necessary for the C5, thus will result in a slight loss of performance in the limited slip ability of the diff. I also believe that aftermarket fluids such as the Severe Gear use a much better basestock than the Dexron LS, thus they will retain their viscosity better over time.