do all mine evety 1000miles..and thats with the best oil one can buy.(vr1 or mobile 1 10-60)...as do gearbox (manual) oil..
my engines look like new inside!..
Sorry to drag an old thread up, but stumbled upon it, it makes a very interesting read.
The main thing with the rover 3.5 is that it has hydraulic tappets, so oil MUST be 20/50 and oil filter and oil should be changed a minimum of every 2500 miles. If not you'll get a very 'tappety' sounding pretty soon, especially if used on short journeys. 1000 miles certainly isn't overkill if you have high power output.