Good evening everybody,
I'm on a holiday with my 95 XJS 4.0, and it seems that it's short of differential oil (strange sounds and vibrations when taking slowly narrow curves). I've read in other threads on this that there is supposed to be a 1/2 inch square male screw closing the filling hole. However, when I opened the access hole in the trunk (great invention!), I found that there is a black plastic cap, and when you manage to take it off, a small plastic plug comes out together with the cap.
I was able to poke a small screwdriver farely deep into the opening, so my question is: Is it possible that the filling hole is only closed with a plastic cap that you can get off quiet simply with your hands? Or is this an opening for some special Jaguar filling tool?
I've attached some photos that show the "discovery" process.
Thanks & best regards
Martin

 

THat is the breather you have levered the cap from. The fill and level plug is the threaded plug with the square centre just to the right of the wire-spiraled thingy.

 

Thanks Greg, I see. Is this the differential without drain plug then? Or do I have to look for it below (not in the photos)?

 

Martin,

The drain plug is on the bottom. Remember not to undo it until you're sure that you can undo the fill plug

Cheers

Paul

 

Here is the filler - fill with oil to the bottom of the hole until it starts to run out, the put in the plug. I can't remember if the recess is 3/8" or 1/2" drive, but it's a standard ratchet/socket set drive. Make sure you can loosen this before removing the drain plug on the bottom!

 

Thanks for reminding. Actually, first I wasn‘t able to get the filler screw out, inspite of having managed to get the ratchet wrench (its 1/2“) into the plug, through the inspection hole in the trunk. The problem was that I wasn‘t able to apply much power, due to the narrow inspection hole and the limited angle of action.
I then used a second jack (fortunately I had one of those which have a simple vertical tube that is winding up, from my old Land Cruiser), and put it below the car, just at the end of the wrench handle Winding it up, I managed to open the plug.
Next problem: not one drop of the needed oil (LS!) available on the entire balearic archipelago. They told me that the could get me some „within a couple of weeks“.
As I am driving back to Germany within a couple of days (1200 kms), I bought a litre of what seemed to be the closest choice: Fuchs Titan Sintopoid FE 75W-85 (API-GL5, but not LS). Some 250 ml went into the differential before the oil started dripping out, and I hope that mixing in the Titan oil won‘t cause problems - what do you think?

 

That oil should be fine.

 

I thought the Fuchs Sintopoid FE was for non-LSD boxes? If you use that oil shouldn't you add a friction modifier for your LSD?

Cheers

Pail

 

He probably should but adding 250ml to the diff isn't that much. Better to have a slightly incorrect oil than low oil!

The Jaguar differentials are a bit different too, the clutches of the PowrLok stay locked until they need to unlock, such as going around a corner, and it unlocks by mechanical means. It's a different operational concept compared to a typical US cars locking differential that relies on clutch slippage to go around a corner. At worst, there might be some chatter of the clutch plate when going around a sharp corner, but for highway driving I doubt there would be any noticeable difference. American Fords for example use fibre clutches, like in an automatic transmission, whereas Jaguar is all steel clutches.

I looked up the manual I have for another Jaguar and it makes no mention of needing a friction modifier for the locking differential. It just says to use a GL5 oil, of 90 weight.

 

As you probably know, JB, not all Jaguars had LSDs fitted. But for sure, the addition of a little ordinary stuff will make no difference to the OP's unit.

 

Good morning,
thanks a lot for your advice!
This is what my original manual says (the car was originally sold in Germany):


it seems that Shell recommends the use of Spirax A90LS when no Spirax 90 is available (see https://www.jaguar-forum.de/forum/vi...9d5c8d98c190e4 - in German).
I‘m not sure whether the original Spirax Super 90 is of LS type?

 

Yaquiyagua,

This i a response from a Shel representative on a different Jaguar forum 20 years ago:

"Spirax Super 90 has been around for years and is based on 20 year old FM technology.

Over the last few years I have developed with Dana Spicer (formerly GKN) and Jaguar a replacement for Spirax Super 90 using new additive and FM technology .

The result is Spirax Thermally Stable Super 90 which is used as Factory Fill for all Jag LSD rear axles.

Spirax Super 90 is currently being withdrawn and replaced with Spirax Thermally Stable Super 90.

The new product has the following Part Nos

Unipart - 900687
Jaguar - JLM 20237

Hope this helps

Best regards,

James Halligan
Business & Technical Assistance
Shell U.K. Oil Products Limited"


So, from that it seems that Spirax Super 90 had FM (Friction Modifiers) and was originally designed for LSDs and subsequently superseded.

Now that you've already put some non-LSD oil in, I would syringe some out and put a friction modifier supplement in there.

Cheers

Paul

 

I should have mentioned that was the recommendation for the LSD type. It was basically the English version of the photos of the manual that was posted.

 

Thanks for all the information. The Spirax oils seem somewhat hard to find, and if you find them, you have to buy 20 liter barrels…
I think I could possibly do the oil change with https://www.liqui-moly.com/en/gb/hyp...0221.html#1410 that seems to comply with all requirements.
Would you agree?

 

Yes, the Liqui Moly would be fine. You can either use an oil designed for limited slip, or an oil that isn't and add a friction modifier - different paths to the same place.

An example of a friction modifier: https://www.motorcraft.com/us/en_us/...modifiers.html
They are usually about 100ml bottles. There are a number of brands, Ford, AC Delco, Dana-Spicer, Redline etc.

 

As the modifier almost costs as much as two liters of the Liqui Moly Oil (at least in Germany, ), I think I‘m better off changing the oil once I‘m back home. No modifier available anyway here in Mallorca…