The oil of choice by Jaguar dealers used to be Magnatec of a specific type ( as you say details in the handbook) but I had Castrol Edge put in mine by the Jaguar dealer who now use it as a matter of course as it supposed to be better ( kinder to turbos???) Either will do , the more often the better. My diesel car only does 2 or 3 thousand miles a year but I still change the oil and have it serviced yearly.
As I may have mentioned before Barry I do all my own servicing, I use the oil spec that's in the handbook which is Ford oil, but next service I might try that Castrol Edge. I only do about 4000 mls a year, so change the oil yearly.
Not noticed any difference with Castrol Edge in the car but then it is impossible to tell if it is doing the engine any harm. Your mileage is similar to mine and the main thing is regular oil changes, especially with a diesel, it can't do the engine any harm but a tip is not to fill the oil up too high. Sometimes problems with the DPF can cause diesel to get into the engine oil and take the level over full which can then blow up the engine. So keep a close eye on the level.
I could do the service myself as it is technically possible to do all engine stuff from under the bonnet if you use an oil pump to suck the old oil out. Everything else is under the plastic engine cover which just pops off, or around the engine bay( air and pollen filters)
I did not bother with trying to do it last time as my local Jaguar garage did a major service and brake fluid change for £260. They admitted they had under quoted when I rang up but stuck to the price on the day. It is good to get a good deal!!
Thanks for the info. Im going to use GM 5w30 oil same spec as recomemded in the handbook , but as i work for GM i can get discount 5ltrs for £20 ( retails at £57 in my local dealership !) . ive used GM oil in all our vehicles even our 1971 Land Rover with no problems , ill let you know how it turns out