I have a 2000, Jaguar S-Type, 4.0 liter engine with
40,000 miles on it. It overheated about a month ago and was leaking coolant. Found the probelm;
a cracked reservoir and replaced it as well as new hoses. The problem ceased but after a few days came back. Nothing is leaking. I powerwashed the radiator grille. The circulating pump is functioning properly. I had a similar problem with overheating back in July and replaced the thermostat. I am at a loss as to what else it could be. Somone did suggest it could be the coolant since my wife had filled it with an allpurpose coolant compatible with any color after the reservoir problem and the manufacturer calls for the orange or (red) coolant. Should I try draining and refilling the coolant? I find it hard to believe the difference is coolant could cause this overheating problem but you tell me? What else would you suggest? Note: even where the gage is showing close to the red zone, the engine temp is still only
around 220 degrees. The heater is functioning normally.

Thanks!