A good quality 75w-90 will be fine. The attached study will give you a lot of info on various transmission oils (good and not so good) so you can make a decision which one to use.

 

Thanks for sharing.

I am an Amsoil user and appreciate their products. I called them today, but they could not find the specific differential oil for my the 1998 Jaguar XJR. I conducted a search on search on google and this is the only site that provided a specific oil. However, there were some disputes as to whether 75W90 or 74W140 is the correct oil. Without any luck from Amsoil, I called a local Jaguar dealership and the parts customer service person reluctantly suggested that I use Castrol BOT 720. I am not sure what weight Castrol BOT 720 seems to be. Castrol BOT 720 appears to be for later year Jaguars (2006 to XXX, I don't recall the end year) and Land Rovers (I don't recall the year Land Rovers).

After consuming that information, I called Amsoil again and they did some research regarding Castrol BOT 720 and they still could not confirm the weight. Not sure where to go from here-- but I will continue my research. Again thanks for your response.

R

 

I put Castrol Syntrax 75W-140 into mine. The original diff ran a bearing at 140k miles, the oil that came out was black and had the consistency of gravy so i highly recommend changing it as preventative maintenance.

 

 

Hi 1998JaguarXJR,

I am attaching the Vehicle Specifications guide which gives the original fluid specs.

The original differential fluid spec for the supercharged cars was the same as the normally-aspirated ones: Shell Spirax Super TS90. Amsoil offers several gear oils that should be just fine, including Severe Gear 75W-90, 75W-110 and 75W-140, Synthetic 80W-90, and Long Life Synthetic 80W-140. If you're concerned about the higher viscosity at 100°C of the -110 and -140 oils, choose the 75W-90 or 80W-90.

Cheers,

Don

 

'03 XJR diff serviced at 82k miles. Diff fluid was "OK" (no unusual "burned" smell or evidence of unusual contamination). Suctioned out and refilled with Red Line 75-110. Chasing a new "noise", I repeated diff. service at 98,300 miles with BG 75-90 and LSII additive. Turns out "noise-squeel" was S/C and ACC idlers and tensioners. Fixed that, all quiet, BUT I now can hear gentle engagement of LS Diff at slow speed direction changes. Not harsh, but it is there, whereas with heavier Red Line, it was not. Do not plan to "re-re-do" just giving info. PS--No "caning," but sustained cruising 70 to 90+ here in South (US). Car continues to operate/run better than new (now with 100k mi), w/ 6% SC pulley and Mina R exhaust.

 

Did you install the LS Diff, and if so what make?

 

I am planning to check the differential fluid on my XJR (X308, 2002) next week, since the car is on jack stands anyway.
I have no idea if the oil was ever checked, filled up or replaced, so I dont know what is currently in there.
Probably I will end up sucking as much of the current oil out as I can.

Would it be any problem to fill up with some of the current fluid in there? I was planning on filling with 75w 90.

Since the breathers are hard to reach and I cant seem to find any replacements easily, I was thinking not to touch it at all.
Any tips on cleaning it without removing it?

Thanks!

 

I removed the breather, cleaned it thoroughly and re-used it. I did that on a couple of X308 XJR cars. I found accessing and removing the breather is far easier than accessing and removing the fill plug. Once you find the correct path for your arm it’s pretty easy.

 

Thanks Jeff. I will give it a go.
I noted you posted something about the choice of oil. Which one do you recommend? Would it be a problem if they get mixed up? (not sure what is in there now and if I can get all of it out).

 

It’s been 2 1/2 years since I changed the differential fluid in my current XJR but I’m almost positive I used Redline 75w-90. I wouldn’t stress too much about mixing; just suction out every last drop you can and then fill up with new fluid.

 

A '03 (X308) XJR didn't come as stock with an LSD. Unless you've fitted one yourself somehow, I'd be surprised if you can hear the 'gentle engagement of the LS Diff at slow speeds"

 

Replaced the differential oil today and cleaned the breather. Not too difficult, just hard to find the right position. Breather is indeed 14 mm.

Question: I havent managed so far to turn the breather back in completely. There is about 2 mm left between the nut and the differential housing. I feel if I push any further something might break and since breathers cant be ordered anywhere (or at least as far as I know), I was thinking to leave it as it is. I am quite sure it's stuck and wont leak.
Any opinions on this?

 

Hi VivaJag,

Congratulations on your successful fluid change! You are right to be concerned about breaking the breather, especially if the cap is plastic, which becomes brittle with age. I would suggest you drive the car for a few days, then crawl under to see if you see any fluid leaking. The breather sits well above the fluid level and only fluid that is splashed up by the spinning gears has any chance of finding its way out around the breather, so it may be just fine the way it is.

Cheers,

Don

 

Thanks. Makes sense.
In fact my breather was all metal (?)