My '07XK consistently runs at 203F, which is "normal". Jaguar specifies that the OEM thermostat is to begin opening at 190F and become fully open at 203F.
The part number for the OEM thermostat is AJ811788. To my knowledge Jaguar does not offer a "cooler" thermostat.
Underhood air temperature is not a "problem" for me, but I would like to experiment reducing temperature by installing a "cooler" thermostat, say one beginning to open at about 170F. I have made this mod. to other cars with positive, though modest, results.
The '07+ thermostat design differs from previous models, which used a more or less generic design. This thermostat comes in several pieces which are assembled into the "thermostat cover" and held in place by two prongs in the thermostat cover and it's base diameter is about 40.5mm. Contrasted a more traditional thermostat base diameter is about 60mm.
I know that mfgs are changing to these smaller thermostats.
Has anyone so changed their thermostat? If so what thermostat (make and part # please) did you use? Did you like the result