I’ve only just bought my 4.6 but nice it rubs nice and cool but almost immediately after I stop in traffic it climbs quickly and fans are on constantly.
God knows what will happen in the summer
Firstly is your 4.6 chipped? If not get it done immediately (if not sooner!) The fuelling chip used by MMC was designed for the 3.9 , and the 4.6 engine ran very weak as a result , and would overheat all over the place. The best ones are designed by Mark Adams and I think they are branded Tornado.
Secondly fit an alloy radiator is almost certainly going to be needed if you are going touring , esp on continent , in summer so that is worthwhile doing sooner rather than later.
Lastly I would still strongly consider fitting an over-ride switch (as discussed here)
My car has an larger alloy radiator, bonnet ventilation hinges, and a fuel chip and the fan will still be on for ages in London traffic. Using the fan switch early keeps the temperature down, so you don't encounter as much high end readings.
One of the problems is that the Rover V8 engine was optimised to run at 85 Deg C initially . In order to comply with ever more stringent emissions regs (which eventually killed it) the engine was run hotter and hotter in order to keep emissions lower
