I bought my first Range Rover 5 weeks ago P38 2001 2.5 DHSE automatic, 1 owner from new full service history 100,000 miles, I have now noticed that the engine is beginning to sound rough first thing do you think it would need an oil change and if so which oil is best, also there is a whinning noise which only is heard when accelerating and above a certain speed 

We have had lots of cars in the past and always done jobs ourselves but never had a Range Rover, I've heard they need regular maintenance more than normal cars is this correct and what would you recommend. I love the car to bits it's in prestine condition and when I've taken it places people comment on it's good condition 