I'm new and looking to buy my first XJS after years of classic bikes. I have read a lot about over heating...of the V 12 which i will be purchasing.
I have a 81 Suzuki Katana bored from 1135EFE to 1230 and have installed a oil temp gauge, being the sump plug which has a temp sensor in it. I know how hot the oil is running and when it gets to 78C (175f) (slow traffic) 69C is normal highway temp, air and oil cooled, but 76+ it getting real hot, also tell alternator voltage, like 14+ volts when running. Quite cool . Down to 11.8v when motor is not running. Could this be helpful?

F) in slow traffic I know the engine is getting hot. Would this work on a V12? Would knowing the oil temp be helpful?

Just a thought, might be completely stupid and i apologise if so.

 

The XJS is fitted with an oil cooler, and oil overheating is not, repeat not, a problem with the engine.
By contrast, the coolant system must be kept on top notch order. If you buy a car, then be sure to remove the radiator, clean out all the fins of the rad, and the oil rad and condenser in front of it, replace the thermostats and ALL hoses (all 14 of them) and have the rad flow tested. If it is iffy, recore it or buy a new one.