I changed out the oil in my front and rear diffs today. On my 2001 discovery with 88k miles on it and I was amazed at how bad the oil that drained out looked. Man it was like a silver milkshake. And the magnets were completely covered in flakes. I honestly believe this may have been the first time the oil was changed. After seeing this it will be put on my yearly things to do list for sure.

 

Some owners move to a heavier weight oil, but you will see various opinions on that. If these looked bad, you'll want to be doing the transfer case anyway, and be prepared for worse.

 

I was going to do the transfer case today but could not get enough clearance for my 1/2 inch breaker bar. Looks like I will need to put it on stands. I just didn't have time to jack it up today. I will try and tackle that next days off.

 

There is a write up in the tech area of the D1 part of the forum on transfer case re-seal of the plate, with pictures. Applies to both. Carefull with the drain plug, not very big, magnetic tip. I used a pump to get the fluid in, someone talked about backing up on ramps or lifting the back of the truck to get a little more fluid into the transfer case. I went with syn 140, seems quieter. On the D1 there are also little air vents for the diffs, these need to be kept clean and there is a banjo bolt on each axle near the diff that feeds them. If they clog up the diff oil can be forced through wheel seals.

 

Easiest way to get to the transfer case fill plug I have found is with a "serpentine belt" rental tool available at most auto parts stores. It's a flat bar with a 1/2" adapter at the end. Had I known discovered this before I changed my transfer case fluid, I wouldn't have cursed nearly so much.

 

Thanks for the tip. I will pick one up and give it a try. I was wondering how I was going to fit my breaker bar in such a tight space.

 

John,
switch your oils over to an 85W/140 for better wear protection on both the diffs and the t/case.
Start changing them evry 20,000 miles or so to prevent any more milk shakes and more frequently if you do lots of water crossings.
As for the metalic mud you found on your drain plug, that is normal with the lighter gear oils and is OK as long as there are no chunks in it. By switching to the heavier oils you will find less and less mud on the magnet.

 

With the crossmember removed I've always used a 1/2 rachet on the plug with no problems.

 

This might be of help. When i changed my fluid I used my breaker bar with a 8-10 extention and a 1/2 universal joint in the end. From the rear of the transfer case you can reach right over everything to get to the fill plug it just does not line up 100% which is were the univeral joint on the end comes in to play. I really was quite easy that way and no need to remove the crossmember at all.

 

Thanks for all the tips guys. Y'all make owning and maintaining a disco possible.