Welcome to the forum Neal.
I have a Sovereign 2:2 6 speed auto, with this auto we have a Diesel Particle Filter and the engine oil that should be used is a Low Ash C1 Oil the number is WSS M2C 934 B and this number is not mentioned in the Handbook. They fitted the DPFilter to get the emissions down and it was fitted as a optional extra on the manual gearbox and they never told jaguar dealer's what Oil should be used, Miller Oils used to get Dealer's asking them what Oil should be used.
There has been some debate about what Diesel should be used, some jaguar owner's add some additives to normal diesel and other's use Premium Diesel which i try to use at least every other tankfull.
Some members like to change all fluids and filters after they have bought there car and they then know that it's something less to worry about.
They say the auto gearboxes are sealed for life which is not true, the gearbox is an Aisin Warner make and to change the fluid it is best to get it connected to a Hot Flushing Machine, i had mine changed at Mackies Auto Transmissions in Glasgow in July 2014 and cost £154 pounds and will probably get it changed again this July.
When a Regeneration of the Diesel Particle Filter is taking place it's sometimes difficult to know that it's happening, the way i know it's happening is the engine Revs will be about 150 higher than normal when the engine is idling and when a Regeneration is happening don't switch the engine off and carry on driving till the Revs are back to normal, i usually check the Revs at a junction or at a roundabout and in 6 years i've only had to carry on driving 3 times. Another thing would be a burning smell or the exhaust could sound louder than normal as if there's a hole in it.
You have a nice looking x type ,they're great cars so i hope you have many years enjoying it.
Regards Tom .