Long Life Rear Axle Fluid

[roegs]

I’ve searched all through my ’03 owners manual to find the schedule for changing the rear diff fluid when towing. So far, there is no mention. I think I now know why. After taking a look at the window sticker that came with my truck, I see it mentions ‘Long Life Rear Axle Fluid’. Must be a new marketing thing with GM, just like Dex Cool. Its amazing that the same purple fluid that last year needed to be drained after 500 miles of towing can now go the life of the truck.

[huntindog]

roegs
It is not stated in the manuels for any of the years.
Having heard all the horror stories on how bad our fluid looked after 500 miles, I decided to see for myself at 24505 miles.
I now know why GM doesn't recommend changing it. The fluid looked totally normal, without any of the burn't smell I usally experience. The magnet was the cleanest I've ever seen, with just a little grey mettalic sludge on it. Yes I checked and the magnet is strong.
And these results are with fairly frequent heavy towing.
This by far was the best looking fluid/magnet that I've ever seen, and I have done a lot of fluid changes.
My conclusions are that this synthetic fluid is really good, and the rearend should last a very long time.
It will also be a very long time before I do it again. Kind of a shame that the easiest one I've ever done turns out not to need it very often.

[ 04-16-2003: Message edited by: huntindog ]</p>

[roegs]

Huntindog...my experience was different than yours. My '00 manual specifically stated in the towing section that rear diff fluid should be changed after the first 500 miles of towing. While the drain plug was not completely loaded with shavings, it had enough on it to make me glad I did the change. As you mentioned, it’s an easy change to do, and for me, its pretty cheap insurance against future problems.

[dmaxalliTech]

03 owners manual makes no mention of changin fluid. If anyone is interested though, I can get 7 quarts of grape juice, enough for front and rear and the updated white vent connector for 139.95 shipped to your door

[huntindog]

roegs,
00??? That's a totally different truck, which probably didn't even have synthetic in it.
My 01 manuel has NO mention of changing the fluid.

[JimWilson]

I seem to recall a mention of changing it after 500 miles of towing, or at the first service. I don't know if that was in the manual, or maybe it was the salesman. But I did hear that before I started poking around in these forums.

I changed the rear at 1K and the front at 3K. The rear had some crap on the magnet, but not a lot. The fluid stunk like sewage though. The front didn't have much smell, but boy was the magnet full of gunk. There was so much it looked like it was wearing a sombrero! I'm glad I changed both of them, that's for sure.

[huntindog]

JimWilson
Your experience backs up my point, the front doesn't come with synthetic. The smell was probably the grape scent that GM put in on purpose.
On another note, I am aware that Eaton ( the manufacturer of the rearend ) has a bulliten out stating a change at 500. That is where this rumor started. I read it a long time ago, and it just occured to me, that maybe they were refering to this change when using conventional fluids!

[huntindog]

I just got back from the Eaton website.
I could find NO mention of synthetics.
I even tried using the search feature with no luck.

[jbplock]

See these links for more info...

http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=002814

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=7&t=004614&p=

smile.gif

[huntindog]

jbplock
All these links do is repeat the same rumors, in some cases cut and pasted. One post sends you to the Eaton site, where there is NO mention of synthetics.

[Tsckey]

I just changed mine (14+K mi.). It was black at I expected, but didn't smell burned, though grape scented gear oil is an interesting fragrance all by itself. I used Mobil 1 Synthetic 75W-90. It took slightly more than 4 qts. I drained out around 3 qts. Where does it go? No signs of leakage. Maybe GM gave me a short fill. The magnet had only a little fuzz, which was encouraging, but there were also a few larger particles about the size of a small grain of sand that I had rather not been there. I decided against the GM lubricant because, like their shock absorbers, I figure they do not put premo products in at the factory when they don't have to. So I did it for them, er, me, actually. I'll do the front diff next.

TC

[jbplock]

Huntindog,

I don’t think TXDoc’s post is a rumor. He posted a quote from an email reply he received directly from Mr. Ralph Holmquist of Eaton regarding service of the Eaton locker.

TxDoc seems like an honorable fellow to me, and I assume he posted this information in good faith assuming it was accurate. If you’re still concerned, maybe you could email or call Eaton and verify this info (?).
smile.gif

[huntindog]

jbplock
Actually, I'm not concerned at all.
Just pointing out that anyone can post anything very easily on the net. Then it grows a life of it's own.
Maybe it's true or maybe not.
The fact remains that it's not recommended by GM, or on Eatons website.