Changing your diff oil, Discovery 1 300TDI

How to change your Differential oil on a Land Rover Discovery 1 300TDI

This is a brief explanation of how I change my diff oil on my Discovery 1 300TDI. This really is simple to do and takes approximately 30 minutes for both diffs, providing you do not have the issues, I did.

It’s really important to change your differential oil at 6,000 mile intervals or sooner if you do any heavy off roading to ensure your Land Rover performs as well as it can.

To do the job you will need;

•  A bowel to drain the diff oil into
• A ratchet 1/2" or 13mm
• Fresh EP80/90 mineral diff oil in one of those poring bottles

Firstly take your Land Rover for a drive for a few minutes to get the diffs warm, and then park on a level surface where you will change the oil.

You then slip a bowel under the diff you are working on and undo the bottom drain plug, this is off centre on the bottom left of the picture below, you can see a diff guards here.

Land Rover Discovery Diff with Diff Guard

The old oil will drain into the bowel, leave to drain for a few minutes until it stops. I use two bowels so I can nip to the other end of the car and do the next diff. When your diffs are empty you will need to put the drain plug back in, and fill with EP80/90 oil until the oil come out of the filler hole, this is the one you can see in the picture below.

Differential filler hole.

Now, what happened when I first did mine was pretty odd, firstly the drain plugs were seized, I had to use the Land Rover Bottle jack and a breaker bar to crack the drain plug bolts loose, it was not as bad with the filler plugs they came out with a good heave on the breaker bar.

My rear differential oil came out washy and green, this is where water had got into the diff. The front diff oil came out looking like black goo.

This should not be the case with either diff, basically at some time in the past the rear had got wet. The good news is, I had no metal coming out of either diff.  So I can only assume the last service I had done the dealer had not changed the diff oil although it was reported as being done on the schedule Grrr.

Look at the colour of the mixed oil below, this is not a reflection of the clouds, that’s the oil from the rear diff.

Water contaminated diff oil, YUK!

Also a tip, but your oil in 5ltr bottles and get a 1 litre bottle to use as a filler. This will save you a lot compared to buying loads of 1ltr bottles.

I use Comma diff oil, because its good quality, cheap and therefore I will not hesitate to replace it. In fact because my rear diff oil was really bad I will be replacing this in 1,000 mile and then at 5,000 mile just to get any remaining crap out.

That’s it simples!