rear end fluid change

[fanzdslpwr]

i want to change the oil in my rear axle on my 2003 3500 with 3.73 rear. i know it takes synthetic 75w90. does it also take any additive? how many quarts do i need to replace the fluid? i am going to suck the old oil out with a oil hand pump.

[DonG]

fanzdslpwr,

You do not mention if you have the G80 option, (Eaton Locker). As long as you replace the gear oil with the type that meets the specs for your rear end, there is no additive required.

The volume needed is 4 quarts.

There is a bottom drain so you do not need to suck out the old fluid.

Hope this helps...

Don

[jbplock]

As Don said the rear diff will hold 4 quarts after a drain (alldata lists the spec on my 03 as 3.83qts). However, there have been some recent posts reporting that GM is has directed not to fill the diff to the top of the hole.. See posts by madmatt in the the following thread Rear Axle Fluid Level (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=7;t=006354).

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[fanzdslpwr]

the saleman told me it was a locker. i didn't see the drain plug, what size is it? how can i see for sure if the rear is a locker?

[DonG]

It has been too long since I crawled under the truck and looked at the size of the drain plug. Sorry.

If you look at the door of your glove box it should list the options your truck was built with. Option G80 is the number of the Eaton Locker.

By the way - there has been some wonderful information on this site about the Eaton Locker. Use the search feature and do some reading on the topic.

jbplock is right about not filling all the way to fill hole. Stop about 1/2" to 3/4" below the fill hole.

Don

[jbplock]

The magnetic drain plug is on the bottom-center of the diff housing. IIRC a 3/8 rachet fits the socket in the plug.

Here's a picture ...

Front & Rear Diff Plugs (http://community.webshots.com/album/65684589edLUNA)

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[fanzdslpwr]

thanks for the help