Tips on changing the Rear fluid

Delaware · January 21, 2004

Any tips or tricks on changing the Rear Fluid? 03 Silverado 2500HD ...

Thanks

1BADHD · January 21, 2004

Use a gasket, not RTV. Dont buy the purple stuff at GM. You can get synthetic for half the price at auto parts stores. Does the exact same thing. Dont over fill it. Try to use a carb cleaner or something to get all the old fluid out or the bottom of the pumpkin. Its where a lot of shavings settle. I think thats it........oh yeah. Its looks like and smells like crap!!

Roofer · January 21, 2004

One thing I did was drive it around for a bit to get it warmed up so it drained easier. Then after refilling with Mobil 1, I drove it around some more, doing some turns to get the fluid going side to side. Then I checked the fluid level again and added as needed.

JayMan · January 21, 2004

Only take the sheet metal cover off if you want to inspect the G80 "locker" or if you want to inspect the magnets for chunks. I took my sheet metal cover off at 600 and 1,200 miles, and finding very light shavings even after heavy towing, have just used the drain plug at the very bottom of the pumpkin since.

Or do the new trucks no longer have drain plugs??

Use caution when using a solvent of any kind to clean out the bottom of the pumpkin. Unless you carefully use lots of gear oil to rinse the solvent out, the solvent will try to mix with the fresh gear oil and foam up. This will cause problems with gear scoring.

bigdogs · January 21, 2004

I'll have to look and see if my 2003 Sierra has a drain plug or not, that would be nice if it did as the first one I had that has one...

As for solvent, something like MEK or acetone should evaporate out pretty completely and leave little if any residue behind. The lower solvents like paint thinner, toulene, etc., leave more behind. The plus side of toulene is that it is also used as octane boost

heavyduty guy · January 21, 2004

how often are you suppose to change the rear oil?

Delaware · January 22, 2004

The only reason I'm looking at changing it is that I read to change it after 500 miles of towing. I've towed probably 400 milse since getting the truck back in aug 03, but have a lot of plans for the summer with our 30ft TT. I'm looking for tips and some guidance to do it myself beacause I was quoted by 2 dealerships between $120 to $170. Seems like a lot, I havent priced the synthetic fluid or a gasket as of yet, but If I can even save $50 I'll be happy.

99silveradoz71 · January 22, 2004

Another thought I'd throw out is to get a marine type pump that goes on the top of the bottles and allows you to pump the fluid in easily vs. having to work at odd angles.

Roofer · January 22, 2004

Another thought I'd throw out is to get a marine type pump that goes on the top of the bottles and allows you to pump the fluid in easily vs. having to work at odd angles.

Yes, use something like that. The front axle is a PITA to fill. I used a small 1/4" hose attached the the cap with goop. It still took me awhile to fill it.

lbzrcks · January 22, 2004

I drained my rear end oil yesterday on my 04 D/A by just unscrewing the drain plug. But I have one question.... I know that there is supposed to be shavings and what not but mine had a couple pieces that looked like gasket material, is that ok? Plus how many quarts do you usually put in? I put four.

Super Chevy · January 22, 2004

My 03 2500HD 4WD has the drain plug...and its magnetic. I would not pull the cover off unless you find something unusual on the magnetic drain plug. Drive around to get the fluid nice and warm and the job will go quicker. Hardest part is getting the fluid back in. I used a funnel with a hose attached and it worked fine. Took about 15 min. total to complete the job.

Good Luck!

JayMan · January 22, 2004

I'll have to look and see if my 2003 Sierra has a drain plug or not, that would be nice if it did as the first one I had that has one...

As for solvent, something like MEK or acetone should evaporate out pretty completely and leave little if any residue behind. The lower solvents like paint thinner, toulene, etc., leave more behind. The plus side of toulene is that it is also used as octane boost

Good point! BTW: things warmed up in WI yet? That blizzard and windchill must be nasty for you.

Please use PVC gloves when handling Methyl Ether Ketone: that stuff can be absorbed by your skin and cause health problems at longer exposure. A quick peek at the MSDS should scare the bejeezus out of you.

I just used paper towels to blot out the bottom of the pumpkin. Since I did the initial change at 600 miles, I didn't expect to find heavy sludge. It was clean as a whistle. Same at 1,200 miles.

I might pull the cover off this fall just to satisfy my curiosity. If you do the initial change real early, the synthetic GL-5 gear oil really won't allow sludge to form at all. On Eaton Dana HP-40 tandems, I've never seen sludge even at 500,000 mile drains.

JayMan · January 22, 2004

how often are you suppose to change the rear oil?

I did my initial at 600 miles, then started heavy towing (7,200 - 9,200 lbs). Per the Helm Shop Manual, I changed it again at 1,200 miles.

I like a routine of every Sept, since I have the G80 "locker" and like fresh LS additives in it before winter and snow/ice.

I use Mobil 1 Gear Oil 75W-90 for the rear axle plus one tube of CRC Trans-X Posi Trak additive. The lube is $5.25 at the Mobil distributer, the CRC is $7.50 at NAPA, so it costs me about $26 every year. That's pretty cheap insurance.

JayMan · January 22, 2004

The only reason I'm looking at changing it is that I read to change it after 500 miles of towing. I've towed probably 400 milse since getting the truck back in aug 03, but have a lot of plans for the summer with our 30ft TT. I'm looking for tips and some guidance to do it myself beacause I was quoted by 2 dealerships between $120 to $170. Seems like a lot, I havent priced the synthetic fluid or a gasket as of yet, but If I can even save $50 I'll be happy.

Yes, the official Helm Shop Manual strongly recommends a change within 600 miles of towing for the first time. Check my previous posts on this thread on how often I service mine. It's cheap if you DIY.

Sounds like the dealer - or "stealer" - is charging labor and their $25/quart Goodwrench Synthetic 75W-90 gear oil. If you have the RPO G80 GovLok "locker" rear end, you MUST use a synthetic lube with the proper additives. Mobil 1 Gear Oil 75W-90 works for mine. Otherwise, any 'ole synthetic 75W-90.

I pay $5.25 a quart for M1 Gear Oil at the Mobil distributer, so your savings will be substantially more than $50. More like +$100. Take the missus out for supper. Or buy the kitty a new toy.

Remember I would only recommend taking the sheet metal cover off to check the magnets inside for unusual chunks. If nothing is stuck to the drain plug, don't worry about it. It takes about 20 more minutes to wrestle the sheet metal cover off, scrape the gasket off, inspect and clean the magnets on the cover, fit a new gasket, and put the stupid thing back on. Maybe check it every 4 years??

JayMan · January 22, 2004

Another thought I'd throw out is to get a marine type pump that goes on the top of the bottles and allows you to pump the fluid in easily vs. having to work at odd angles.

You know, I've never had a problem filling the rear axle. Mobil 1 Gear Oil 75W-90 comes in a round quart bottle, and they have a fill tip.

You take a dyke (Electrical plier/cutter) and snip about 1/4 inch down from the tip. Then poke the tip in the fill hole, tilt the bottle up, and it drains very easy.

Oh, but make sure you remove the fill tip from the bottle before starting this procedure: there is a sealed cap on the bottle and you'd look awful silly trying to force gear oil out a sealed bottle. Haha, at least I did first time.

From the time I use the square drive to remove the drain plug to when I put the fill plug back on: 10 minutes taking my time. It really is painless, far easier than an oil change.

That's a good tip for the front axle though. It really is impossible to get the lube bottle at an angle where it will fit into the fill plug, as the frame/stab bar is in the way.

Since I have pails of commercial Mobil MobilLube SHC 75W-90 in my shop, it's painless for me to roll the pail over to the truck. 4-5 pumps of the lever and the front axle is full.