tips for changing rear diff fluid

**biker Wayne** · 10-02-2003, 09:43

A couple of years ago there was quite a bit of discussion about changing the rear diff fluid. Search facility doesn't find anything because the messages may be too old. Can anyone give me tips on changing the diff fluid? What is the recommended change interval? Anyone using the Amsoil series 2000 75W90 gear lube?
Thanks.

Heartbeat Hauler · 10-02-2003, 12:01

Change it after the first 500 miles of towing, then as the manual suggests. I would use the GM oil for warranty purposes. This is not to say that any aftermarket products are bad, there just some wierd stuff about specifications as per GM. That's my $.02 worth.
JP

**ski** · 10-02-2003, 12:12

not sure if mechanical tips are what you are looking for, but consider these:

1) get a 6 or 7 foot piece of tubing and pour the gear oil from a standing/kneelig position at the side of the truck. This is the easiest way to refill.

2) checkout gmpartsdirect.com or dmaxallitech (member here) to get the gm syn fluid (aka grape juice)

no warranty concerns and it is good stuff.

**dmaxalliTech** · 10-02-2003, 13:41

Originally posted by Heartbeat Hauler:
Change it after the first 500 miles of towing, then as the manual suggests. I would use the GM oil for warranty purposes. This is not to say that any aftermarket products are bad, there just some wierd stuff about specifications as per GM. That's my $.02 worth.
JP

You would think that GM would have a service interval for changing diff fluid... I havent seen one

Anywho, just like H/H says, after 500 miles, then I would go around every 50k after that

**Phil B.** · 10-02-2003, 19:14

I change my fluid every 25K and use Mobil 1 synthetic gear lube. The only tech tip I can offer is to invest in the top hand pump for the oil, otherwise it can be a pain.

Phil B.

**Lonewolf867** · 10-02-2003, 19:44

This is a little off topic. But I have heard some folks say that the GM grape juice was really Royal Purple Syn Lube...Anyone have a comment or can confirm that?

As for changing I changed at 500 miles and went with the Amsoil. Changed again at 3500 because of a LONG pull from Georgia to Wisconsin. (Just made me feel better). I will probably change again at 10k then at every 25-30 k after that.
USE A PUMP!! Trying to puor that stuff is a PAIN!

Mike

**Kent Tuttle** · 10-03-2003, 10:24

Changed mine at 500, 15K, and 30K with the Amsoil series 2000 75W-90. I know a little excessive but what the heck. I also added the Mag Hi-Tech diff cover at 15K which makes changing the fluid a snap and almost doubles the capacity.

**JimWilson** · 10-03-2003, 18:55

I changed mine at 1K, and I'll do it again at 50K (and then every 50K after that). I'm running Amsoil too.

**1822** · 10-04-2003, 02:12

Also if you tow should be useing 80w/140 syn. Was just at my dealer and he uses Mobil Syn gear lube in his shop.

**VA_Dmax** · 10-08-2003, 02:13

Maybe Im just blind and missed it, but on GMpartsdirect.com it lists "1 unit" for a bottle of the rear diff fluid. This is just 1 quart correct? So we would need 4+ bottle of this stuff for a change? Thanks

**DonG** · 10-08-2003, 15:21

VA_Dmax,

You are correct. One unit is one quart, and you need four quarts. When I ordered the heavier gear oil (85W-140), their minimum order was a case containing 6 quarts.

You might give dmaxalliTech a call on this subject. You can find his e-mail on several posts.

Don

mark45678 · 10-08-2003, 16:24

I know changing your rear end fluid a 500~1000 miles sounds early but I had ALOT of fine metal in the lube! plus I would like to add my .02 take your truck for a 5 mile ride then drain it right after ,this will keep all the bad sh*t up in the oil rather then let it settle out....a pump is a plus also!

**max out** · 10-10-2003, 14:23

was reading were va max said you need 4+ quarts to fill rear end . just wondering you drain from bottom plug, then fill at plug located on rear cover untill it's coming out of plug hole correct?

**DonG** · 10-10-2003, 18:17

max out,

You are correct. The bottom hole for draining. (Make sure you warm up the differential by driving several miles first). The rear hole about 1/2 way up the back is for refilling.

You fill until it comes out of the fill hole, or just slightly below the fill hole. It took me 3.9 quarts to refill mine, not 4+.

NOTE: There is a magnet on the drain hole plug. Clean it of metal shavings and re-use.

Don

**Cliffee** · 10-10-2003, 23:33

Very simple. Remove the drain plug and let it drain. I like to jack up one wheel at a time for about 15-30 minutes to get out any fluid in the axles as well. Use one of those small fluid pumps to put the fluid back in. You can get them very cheaply at harbor freight, etc. After filling up go do a few figure eights and come back and check level again. I changed mine at 5k and added a Magnetic Super Plug drain plug. The magnet on this thing is very strong. It will catch anything in the oil for sure. Its well worth $20.00 I used the Amsoil fluid. http://www.superplug.com

[ 10-11-2003, 10:53 AM: Message edited by: Cliffee ]

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