I emailed Jag re diff oil, they quoted $66 Canadian per "bottle" for part number JLM21847 - presumably just under one litre - buying 2 would leave around 750 ml.

JLM21847 as far as I can tell is Castrol SAF-XJ, which superseded by Castrol Syntrax Limited Slip 75W/140 (Formerly SAF-XJ 75W/140). Not sure which they are selling the old or the new.

However, the new Castrol specs as MIL-L-2105D, which was superseded by MIL-PRF-2105E and then superseded by SAE-J2360-1998.

Pennzoil Full Synthetic Axle & Gear Oil 75W140

Pennzoil PlatinumŽ Axle 75W-140 meets all the requirements of API Service Classification

API GL-5.MT-1
SAE J2360

I'll be going with the Pennzoil at $28.99 Canadian for a 946 ML bottle.

 

On a 14 year old car, I'd say Diff Oil is Diff Oil. Since no clutches, no modifier required on a 4.2 car. As long as the viscosity is close, I'd say use whatever you want. I used Valvoline with a modifier in my 5.0 /R and foresee zero problems until the end of times.
Hellz cheaper than OEM anywyay.

 

I did look at Valvoline Cee Jay, I didn't see where it conformed to the later SAE-J2360 spec. I'm sure it would be fine. I looked at the Ford diff oil. No mention of the SAE-J2360 spec. They use their own - WSL-M2C192-A, which as far as I good find is it complies with MIL-L2105-C/API GL-5

 

Coincidentally, on my first fluid change I went to Lucas…. on the second, to Royal Purple.
In summary, I spend more than the Castrol equivalent.
I can tell you that I’ve never had any issues back there. Bearings and seals are original. Surprises me, really.

 

I used Valvoline and seems to work fine after about 8k miles. Easy job but a little fiddly due to cramped access. See this link for my experience in changing the diff oil.
https://www.jaguarforums.com/forum/x...4/#post2251156

 

Yeah…. the very reason why I want a drain plug tapped in.

 

Yes, that would definitely been easier to drain.

 

Well, considering it's done once or at most twice in the life of the car (unless you're tracking), sucking it out is not that much of a hassle.

 

. I change it more frequently than that. Ditto for the other so called long life fluids; the transmission, power steering, brakes, coolant.
Besides, there’s something just so pleasing knowing that the crap settling at the bottom of the case flows out. (yes, even on the new engines, I have the oil changed by draining from the drain plug and not the siphon tube.)
I attribute this as the primary reason my car is in such good mechanical shape, with original parts and with so many miles.
(ok, ok, bushings, batteries, brake pads and catalytic converters don’t count)

The LR I picked up was kept to the “factory schedule”. Don’t ask how much I’ve put in bringing it up to snuff.