I have a 2.0 diesel seat Leon FR. I had the cam belt and water pump changed by a friend about 3 months ago. Not sure if the following are due to this. I noticed a relatively noisy ticking sound at idle. Once I increased the revs to 1000 it disappeared. I had a oil change done at the same time. I decided to put some more oil in today which was the proper VW approved oil & unless I am imagining it the ticking / knocking sound seems to have almost disappeared. Could this be down to the wrong oil been used at the oil change? Next issue. In the 5 years I've had the car I've hardly had to top up the coolant. This morning the warning light was on telling me the coolant was low. Seems a bit strange that this has happened a few months after the cam belt and water pump change. My friend did tell me to keep checking the water after he had done the work. Is there anything to worry about? Could this just be a coincidence?