<LABEL id=HbSession SessionId="172038919">When do you change the oil in the rear end. I have pos-track on a 2003 2500 Chev. with a Duramax. I am towing a Arctic Fox 5th wheel that weights 11500 lbs. pin weight of 1800 but I only got one tow on this rig. I had a 30ft Trail Lite that weight 5500 lbs. and a tongue weight of 400 lbs. The truck now has 11500 miles. </LABEL>


<LABEL SessionId="172038919"> Tom</LABEL>

I just changed both the rear &amp; front differential oil in a 2004 3500 with 2500 miles. Both had some metal fragments but no more than you'd expect. I plan to change both again after we return from Arizona (6400 miles towing a 12000 lb 5th). I'd change yours now, it's cheap insurance. BTW I used Mobil synthetic in both diff's.

I believe they recommend after the first 500 miles dump it and put in fresh high quality synthetic. With a heavy trailer it's also a good idea to install a Mag-Hytek rear cover. Holds a few extra quarts of lube, has cooling fins, and a magnetic dipstick. Those rears get hot when loaded.

http://www.uscom.com/~hoot/cars/duramax/gmc/mag-hytec/images/DSCN1159.jpg

<LABEL id=HbSession SessionId="3944513786">What oil do i use and do I use a additive? The truck is a 2wd.</LABEL>

<LABEL id=HbSession SessionId="2041420078">I changed the oil today. I found only a few shavings and the oil looked like new. I was pulling a trailer that weighed 5,000 and around 400 lbs tongue weight until I got this 5th wheel.</LABEL>


<LABEL SessionId="2041420078"> Tom</LABEL>

You should use a high quality GL5 syn gear lube if you are towing anything. GM recommends 80/140 for towing. I tow a heavy fifth wheel and change the lube every 25,000 mi. with little or no metal flakes in the oil. I use Texaco Syn-Star 80W/140.

<LABEL id=HbSession SessionId="3944513786">What oil do i use and do I use a additive? The truck is a 2wd.</LABEL>


I changed both diff oils over the weekend. Installed a white vent cap in the front diff and pulled off the rear cover and used JB Weld to fasten a magnet to the inside bottom of the cover.





When I went to assemble the cover I found the parts shop sold me the wrong gasket. I spent three hours and 8 shops and never found a gasket.http://www.dieselplace.com/forum/smileys/Angry.gif I finally just used black RTV and it seems to work well.





I used AMSOIL 75w90 synthetic. I will be changing out the Dextron III in the manny and the transfer soon. Anyone know about a good pump for fluids (drill driven perferably)?http://www.dieselplace.com/forum/smileys/Confused.gif The manual pump I used is so slow it will take the entire weekend just to pump 21.4 quarts http://www.dieselplace.com/forum/smileys/Clown.gif into the tranny!!!





Thanks,