I am going to be putting in new oil in the rear diff, but I am not seeing what spec oil I should be using (I cannot get JTIS on my macbook for whatever reason).

What weight oil should I use?
Thanks

 

Hi Bcrary3,

According to the X308 Workshop Manual, which you can probably download in pdf format for free from this forum or jagrepair.com, your car has the GKN 14HU differential and the originally-specified fluid was Shell Spirax Super TS90, a straight 90-weight gear oil. I'm not sure you will be able to find a source for that fluid today (other than something the Jaguar dealer would sell you). Most members don't even bother trying to find it, they just use a more modern gear oil that covers the same viscosity range.

I'm currently using Lucas 75W-140 Synthetic Gear Oil in both our '93 XJ40 and '04 XJR. Similar products are available from most of the major brands like Valvoline, Mobil 1, Amsoil, Pentosin, Redline, Castrol, etc. I've used Valvoline, Castrol and Lucas in our cars because they're commonly available at the local auto parts stores, but your favorite brand will no doubt be perfectly fine.

Search the forum for the challenges you will face in accessing the fill hole on your diff and be prepared with the items you will need. You might especially be interested in the method that involves creating a hole in the trunk/boot bulkhead for easier access.

Cheers,

Don

 

Alright.. I ordered 2 quarts of Valvoline 75w140...

As far as accessing the hole, I am paying someone else to do all of the work,but I will make a note of that (I am paying a shop tech to do it as it is convenient).. But the 75w-140 I see is recommended for the x350.

 

75W-140 works great in our XJ40 as well as our X350, so it should be fine in your X308. The internals of all the diffs are very similar (even going back to the Series XJ6 cars). 75W-90 fluid will also work, but since the 75W-140 gives even greater high temperature protection along with the lower friction of a modern fluid, that's what I've gravitated to.

I don't know if it's possible that your differential is a Limited Slip model, but if so, you'll need to also use a friction modifier additive. The shop will be able to easily tell if your diff is an LS or a standard "open" version by rotating one rear wheel. If it's an LS, both rear wheels will rotate in the same direction. If it's a standard open diff, the other wheel will rotate in the opposite direction.

Here are just a couple of the many threads about changing the fluid in the X308 diff:

https://www.jaguarforums.com/forum/x...ax-ts90-54273/

https://www.jaguarforums.com/forum/x...er-plug-51532/

Cheers,

Don

 

Awesome! I don't think that it's a LSD but, I will definitely check, it'd be interesting if it were, I suspect that it is a standard diff though.

 

There is NO factory equipped LSD beyond MY 1997 XJ Sedans.