owner's manual

scottac · December 1, 2003

I am looking in the owner's manual for how often to change or check the fluid in the differentials. I am not seeing this anywhere. am I just looking in the wrong place or what.

I see where it says to check the fluid in rear/front axle surely this isn't referring to the differentials and 4wd gear box.

thanks in advance for all the replies.

JayMan · December 3, 2003

You've discovered how vague modern owner's manuals are! I guess they want to promote an image of "maintenance free" which they will be until the warranty expires.

My dealer gave me a copy of the "Goodwrench Smart Guide Maintenance Schedule" supplement when I took delivery of my Canadian truck. It's quite specific on how often to change the gear oil:

You're supposed to change the gear oil during the first 5,000km / 3,000mi, then every 20,000km / 12,000mi.

My Helm shop manual also recommends changing it again after 500 miles of trailer towing for the first time. That makes sense as the first time you tow a heavy trailer, there will be additional wear particles.

Aftermarket gear places suggest much stricter maintenance. I've had good luck with Randy's Ring and Pinion, and they recommend a gear oil change within the first 600 miles of use.

When my truck had 1,600km / 1,000mi on it, I changed everything. Front and rear gear oil, motor oil, ATF, and transfer case. But that's just me, I intend to drive this thing forever! FWIW I did it myself and with Mobil synthetic lubes it cost around $165.

Maybe check the fluid levels every time you change the oil or twice a year. Unless you have a leaking pinion / axle seal, it shouldn't go down. You'd see the oil drips on the garage floor if a seal was gone.

I always check the gear oil when the thing has been sitting overnight and is stone cold. I like to fill the axles until gear oil just seeps out. Let it finish seeping out, then put the filler plug back on.

For some reason, GM doesn't want you to fill the rear axle to the filler plug. I always have topped it off and it works fine. Can anybody offer a reasonable explanation why GM doesn't want the fluid level topped off in the rear axle??

There are excellent guides and articles in this forum, so don't be afraid to look around! Look at the top left under "Features."

Good luck!

scottac · December 3, 2003

thanks for all your help jay. I really appreciate all your help.

Like you I also intend to drive my truck until the motor blows up and I will then probably replace th motor.

I just want to get a good jump on the maintenance of a new vehicle

once again thaks for all the help

I may buy that shop manual too and will check out some of the links under features.

JayMan · December 3, 2003

No problem. Let us know how the Maintenance Adventure works out!

ALthough the basics never change, I've found the official Shop Manual critical to understanding how the modern systems work. If you really do intend to keep the thing forever, it's a wise investment.