LSD additive in a 2WD Tahoe LT?

[NW94Z]

I just purchased a 2007 2WD Tahoe LT for my parents and before handing it off to them I would like to give the whole thing a complete overhaul. In changing the fluids I'm trying to find out if I need the GM LSD additive for the diff fluid change?

Other than that I was going to pick up a good 75W90 synthetic diff fluid. The Tahoe has 139K on the clock and I doubt the diff has ever been done. Also going to pull the tranny pan and flush the cooling system.

 

[livingez_123]

if it has an LSD in it, then yes use the additive even with Syn oils. My sure you flush it the proper way so you don't contaminate the new atf with the old. There is a very informative write up on it somewhere here on the site. When changing the diff fluid, buy a couple of cans of brake cleaner and spray the stuffings out of the case and gears. This will help get any debris that is hiding in there. Don't forget to flush out the PS and the brake fluid. DOT 5.1 is a real good fluid to use. Plugs and wires are something to consider.
And good job of taking care of your parents.
My 01 Denali just turned over 135k

 

[NW94Z]

if it has an LSD in it, then yes use the additive even with Syn oils. My sure you flush it the proper way so you don't contaminate the new atf with the old. There is a very informative write up on it somewhere here on the site. When changing the diff fluid, buy a couple of cans of brake cleaner and spray the stuffings out of the case and gears. This will help get any debris that is hiding in there. Don't forget to flush out the PS and the brake fluid. DOT 5.1 is a real good fluid to use. Plugs and wires are something to consider.
And good job of taking care of your parents.
My 01 Denali just turned over 135k

Thanks.

I've got plugs and wires covered and will also be bleeding the brake fluid.

Never done the power steering fluid. How do you flush that? Are you suggesting brake fluid for the power steering also?

Are you saying to avoid contaminating the new Diff fluid with the old or are you referring to the tranny ATF fluid? Dropping the pan and replacing the filter will only remove about a third of the fluid so there will be ATF fluid contamination.

As for the Diff do you know if it is limited slip or not? I would presume on the 2WD rigs it's one or the other.

If reasonably taken care of these things (LS series motor) can last a very long time in my experience. I have 167k on my 03 TB with the 5.3 and it drives like it has 40k on the clock.

 

[livingez_123]

No brake fluid in the PS.
Just saying to make sure you clean the diff out real good.
Try to find the thread about how to flush out all of the old ATF fluid, it will explain.
Check the RPO codes to see if it has the LSD or not.

 

[992dr]

I could have sworn I read that you were NOT supposed to flush the trans.
It is not recommended for our vehicles. I think it states it in the owners manual.

 

[akbrener]

I am pretty sure these things use an Eaton Gov-lock style differential, it is not a true limited slip, but more of a locker type posi unit. Those eaton's do not need the additive.

I think the RPO code is G80 for a non-open differential, that is it for S-10s and F-bodies.

 

[NW94Z]

I've seen comments before about not completely flushing out the ATF fluid or at least not using a cleaner or detergent. I'm just going to pull the pan replace the filter and add fluid back in.

It's probably safer to have the additive than not. I can just put it in and not worry about it. I'll check for RPO G80 tomorrow. While I have parts on order I just did some minor cleaning up tonight.