This can be done on the car although it is easier off the car as you have good access. You need to make sure you can fill the oil again before you drain it so make sure you crack off the drain and fill plugs before you commit to anything!
If you can do this warm it is recommended but not a problem if you can't
Step 1 - Slacken the 24mm fill plug, if you can't do this then you are going to have to find someone who can! I recommend you get a good 24mm socket and a breaker bar for the best chance of an easy removal
Step 2 - Now crack the drain plug off too, it's another 24mm
Step 3 - Position the diff over an oil drain pan of some kind. Transmission fluid is revolting, diff oil is even worse - it stinks. Try not to get covered!
Step 4 - Remove the drain plug and the fluid will start to escape. Remove the fill plug and you let the fluid pour out even quicker. Note the filler plug is different when removed, see picture 2
Step 5 - Wait for it to drain then refit the drain plug
Step 6 - You'll need to get a couple of litres of 75W90 (or 80W90 and I'm sure others will make recommendations too) API GL-5 rated. You can go for semi or fully synthetic, I went for fully. Millers oils are great so I recommend them and everyone raves about Redline too so they're worth considering.
Step 7 - The bottle should have a nozzle to ease filling, otherwise you need funnels or a lubricant gun to help you, pour in the first bottle completely then start on the second (you won't need it all)
Step 8 - When fluid starts to run out you know the fluid has reached the level off the filler plug which is how full it needs to be (about 1.2 litres for me)
Step 9 - I like to give the diff a quick spin before I fire up the car and start abusing the diff again!
For what it's worth, my oil was low and like treacle so needed a change, make sure yours isn't neglected too!
If you can do this warm it is recommended but not a problem if you can't
Step 1 - Slacken the 24mm fill plug, if you can't do this then you are going to have to find someone who can! I recommend you get a good 24mm socket and a breaker bar for the best chance of an easy removal
Step 2 - Now crack the drain plug off too, it's another 24mm
Step 3 - Position the diff over an oil drain pan of some kind. Transmission fluid is revolting, diff oil is even worse - it stinks. Try not to get covered!
Step 4 - Remove the drain plug and the fluid will start to escape. Remove the fill plug and you let the fluid pour out even quicker. Note the filler plug is different when removed, see picture 2
Step 5 - Wait for it to drain then refit the drain plug
Step 6 - You'll need to get a couple of litres of 75W90 (or 80W90 and I'm sure others will make recommendations too) API GL-5 rated. You can go for semi or fully synthetic, I went for fully. Millers oils are great so I recommend them and everyone raves about Redline too so they're worth considering.
Step 7 - The bottle should have a nozzle to ease filling, otherwise you need funnels or a lubricant gun to help you, pour in the first bottle completely then start on the second (you won't need it all)
Step 8 - When fluid starts to run out you know the fluid has reached the level off the filler plug which is how full it needs to be (about 1.2 litres for me)
Step 9 - I like to give the diff a quick spin before I fire up the car and start abusing the diff again!
For what it's worth, my oil was low and like treacle so needed a change, make sure yours isn't neglected too!