Ugly differential oil sludge at 40K miles
 

Here is what my 2014 differential oil looked like after 40K miles. The photo shows about a half quart of new oil on top of the original Jag sludge, since I ran new oil through before filling. The recommended interval is 140K miles. No way. Replace your diff oil ASAP, then maybe every 20K miles. Uhg!

https://cimg2.ibsrv.net/gimg/www.jag...df48013f9c.png

For DIY'ers - you 'll need to access the fill plug from above the black metal plate, going in from the side. Use a ratchet extension with a hex bit. There is a slight approach angle but removal is easy. Reinstalling the fill plug is difficult because the slight angle inhibits re-threading. Using one hex bit down in size allows the fill plug to wobble just enough to get the threads started by hand.

https://cimg3.ibsrv.net/gimg/www.jag...fbe9d4ec13.png

And a tip for young players - make sure you can crack the fill plug BEFORE you open the drain plug and dump it all, otherwise you could be stuck with an oil-less diff and no way to refill it!

Edit - and the diff oil "diff"ers between the base V6 (open diff) and the V6S (mechanical LSD) and the R (e-diff).
From the Workshop Manual:
"ENGINE TYPE OIL DRY FILL
(LITERS)
WET FILL
(LITERS)
Vehicles with 3.0L petrol (340
PS)
SAFXO 0.84 - 0.86 0.815 - 0.835
Vehicles with 3.0L petrol (360
PS)
BOT720 0.84 - 0.86 0.815 - 0.835
Vehicles with 5.0L petrol BOT720 1.24 - 1.26 1.200 - 1.220"

Sorry for the crap formatting, but the main point is the base model with the open diff takes Castrol SAFXO fluid while both the S (with the mechanical LSD) and the R/V8S (with the e-diff) take the Castrol BOT720 fluid.

Unless you opened up the diff and gave it a cleaning, try two differential fluid changes within 1000 km of each other. That will clean it up.

Thanks for the suggestion. Will do. And I'm not using the OEM fluid anymore.

Interested in what oil you're going to use, about to change mine (e lsd) and found Castrol BOT 720 to be difficult to obtain, not even sure it's manufactured now, and rather expensive for a 75W 90 semi synthetic oil containing LSD additive

Was considering using this
https://cimg6.ibsrv.net/gimg/www.jag...54b2e51f81.jpg

I’m running royal purple this season... thought I’d give it a go.

Same here. I put Mobil 1 75W-90 LS (includes friction modifier) in for a cleaning cycle because it was in stock and ~half the price. I'm going to take yor advice and change it again quickly. I ordered some RP Max Gear 75W-90 which includes a friction modifier for LSDs. RP Synchomax stopped my BMW's awful notchy MT6 from not fully engaging and popping out of 3rd. That car is such an incredible POS compared to the Jag.

That looks perfect to me.

Thanks all for these posts and highlighting this issue for attention. My car doesn't have any differential leaks yet, but since it has 33K miles this diff oil change seems like the prudent thing to do.

Seems like the Motul Gear 300LS, 75W-90 would be the right choice for my car and I'm assuming that you fill the diff case to the bottom of the add opening (like I've done on every other car I've every changed). How much gear oil (number of quarts?) will that be?

Also, OzXFR your recommendation of getting the fill plug removed before draining the diff is a good one. A hex bit on the fill plug at the top of the diff, really? Seems like they made that overly hard.

All(?) differentials have the same layout.

• Remove the fill plug, first.
• Remove the drain plug.
• Let it drain fully.
• Pump a few ounces of new fluid through til it runs out clean.
• Replace the drain plug.
• Pump new fluid into the fill plug until it drains back out of the fill plug.
• Replace the fill plug.

It requires almost 2 quarts plus any flushing waste. An auto fluid transfer pump costs $10-$15 at any auto supply store or Amazon.

A hex bit (Allen bit) is the only type of plug I’ve seen on a diff in the last several decades. What type would you prefer?

I have read somewhere, can't remember where now, that "pump new fluid into the fill plug until it drains back out of the fill plug" is not correct for the F-Type diffs.
The specified fill volumes are shown in the Workshop Manual per post #2, and assuming we will be wet filling (not dry filling a brand new diff) they are:
Base (open diff) and V6S (mechanical LSD) : .815 - .835 litres.
V8 (e-diff): 1.200 - 1.220 litres.

Would you believe the XKR is the exact same, with the exact same obstruction and access. You could not tell the two apart.
You would think they would have made a special bent Allen wrench by now or just given us a bolt- an outie instead of an innie.
So glad I found this thread by expanding my search. Came here to get some answers after just giving up and taking the car off the jack stands- will trade you some tips.
1. when you chop off a piece of allen to use with a 8mm boxed-end wrench, did you us a flex-head or an offset wrench, or just a straight short 8mm wrench?
2. What's the trick to filling? I was going to pump it in there.

Yeah 45,000 miles and the e-diff is crunching on tight turns. Change your fluid every 35k miles as others have mentioned. Since the diff takes 1.3l of fluid buy 3 bottles and do two changes if you havent done a change in 50k miles.
Ravenol makes an excellent fluid for our exact e-diff, and you are not guessing if it has friction modifiers or not.

Wish I had another fill plug, I would weld a 8mm allen stub on it.

I guess I'm just used to working on old Triumphs (for the most part) with "outies" not "innies". Probably a little easier to get something on it in tight places.

Thanks OzXFR for answering the capacity question.

I used a long ratchet extension with a T50 end socket because thats what I had laying around. It fit perfectly. A T47 helped me get the fill plug rethreaded, plus a long, flat head screw driver to help coax the fill plug into place while turning it.

You can wedge a scrap or two of painters tape between the hex socket and the hex wrench to make it fit nice and snug so it doesn't fall off the ratchet extension tool when you bring it over the black metal guard plate from the side.

To insert the fill hose, I taped it along the same ratchet extension but with an inch, or so, of fill hose extending past the end. Now you can insert the fill hose from the side, over the top of the black metal plate, just like using the ratchet extension to unscrew the fill plug.

I don't know how you pump an exact capacity into a diff, so I'm good with filling it. It took about that much.

Leave it to modern engineers who've never worked on a car in their life to think you can know how much fluid is inside a closed case without sight glass.

Thanks OzXFR for answering the capacity question.

Here is some info that should be helpful for you all. Includes front and rear differentials. After seeing this I thik I am going to knock this out soon! Thanks for the post.

Hope this helps.

DC

The posts here got me duly concerned so I had my diff oil changed this morning by my local shop (they charged me $112 so it wasn't worth my time). Ran the car on the highway for about an hour ahead of time at 80 mph to get the diff oil hot before changing. At 33K miles no leaks on the diff, oil that was changed out looked like fairly typical diff gear oil to me, not sludge like. Upon pumping in the Motul 300 specified earlier in this thread and getting the car back on the road at 80 mph the rear seemed to have a little bit less hum (now that's scientific isn't it). Certainly not hugely noticeable, but good peace of mind. Thanks to all for posting on this.