2000 LS 4.3 4wd. I have decided that with my upcoming atf flush to go with Moblie 1 synthetic atf. I thought about Royal Purple but can't find enough documentation other than theirs. While I'm at it I better do the transfer case and differentials. How do you change oil in the transfer case and diffs and wats the best synthetic fluids for their application

 

As far as fluid for the transfer case goes, you need to let us in on what transfer case you have. The NV233 (3-button switch in the dash) uses regular ATF. The NV236 (4-button switch in dash with auto4wd function) requires GM Autotrak 2 available from the dealer. Capacities for both should be just shy of 2 quarts, IIRC. Remove the fill plug (upper one on the back of the transfer case) first to make sure that you can put fluid in after you remove the drain (lower) plug. Drain it, then reinstall the lower plug and refill until it pours out the upper hole.

For the diffs, any good 80w90 (or 75w90) gear lube will work nicely. The front diff can be a challenge as some did not have a drain plug so the lube must be pulled out of the fill port. On the rear diff, have a look through the DIY section for a post I made up a while ago on servicing the rear axle in my old 2k Bravada.

Synthetics are a good choice. For information on that subject, I always go to BITOG.com.

 

I have the three button tc. The rear is a posi. Does that require anything special? Thanx for the reply.

 

If by "posi" you mean you have RPO G80 on the SPI label on the inside of the glove box, then no, you do not require anything special in the diff. It is not really a posi, but a mechanically actuated locker.

 

Ill have to look. I just remember the dealer sticker said positraction rear diff I could be wrong.

 

THE CONFUSION ABOUNDS KYLE

 

Look at the sticker on the inside of your glove box. If you see G80, you have the Eaton Gov-Loc rear differential. There was no stock differential offered in the standard s-series vehicles which required a friction modifier.