This happens a LOT in Rovers (I know of others with the 3.9/4.0), usually around 120k. The main bearing goes, causing a loss of oil pressure. By the time the light comes on, its too late. The engine overheats, but the temperature gauge only tests water temp, not block temp. Once the bearings are gone, you need to pull the engine and re-grind the crank and put in new bearings. The cam may also go. In mine the block got too hot, and when aluminum gets hot and cools it actually shrinks. This means you need a whole new block. Good luck. A dealer will charge you upwards off $3500-7000 to do the work. It isn't even worth getting the parts - just get a low mileage wreck and pop a new motor in. Or run it off a cliff and call the insurance company. I'd never by a Rover again, everything on it is cheap and badly made.