when the car is parked on uphill, and I try to move the gear back on to reverse, it becomes extremely difficult. Like you have to put a little effort into it. Once it gets into gear, it makes a loud thump noise....which I don't like. The handbrake pedal is depressed during this time. It was like this the day I bought the car brand new...but didn't think it was too serious. Does this mean I need to add gear oil?
The weight of your vehicle is putting strain on your parking pawl. Apply your parking brake BEFORE putting the car in park. If the problem persists either your brakes are worn out/ maladjusted or your parking brake cables are stretched.