UK Car Repair: noisy tappets, what does it mean, citroen zsara picasso, mile oil change

Question
I have a citroen zsara picasso 1.8 petrol. 4 days ago the engine started to produce a loud ticking noise. I had the car serviced and put an additive in during the oil change, things now seem ok. Is there an underlying problem? what would eventually happen if the noise came back? should I get anything replaced in the engine?

Answer
The lifter noise is common to cars that are driven long distances, allowed to sit for long periods, and not given frequent oil changes. I would continue using the additive and also make routine oil changes at every 3 months or 2500 miles to keep the engine clean and happy. After a while you can go back to a 3000 mile oil change and discontinue the use of the additive. The lifters are used to maintain a cushion between the valves and the valve train in you engine. They also act to lubricate the valve train during operation. The clacking you hear is when dirt and excessive wear prevent them from filling full of oil and maintaining their pressure. The additive serves two purposes in that they thicken the oil and also add detergents to break up varnish and mineral deposits in the engine. Thus allowing the lifters to fill and causing the noise to go away. If you are concerned about the problem regardless of if it will clear itself up with more frequent oil changes you will not detrimentally affect the engine by using the additive every time. Should the noise come back regardless of the additive you will need to have the lifters replaced. I am unable to offer an idea on cost and advise you to shop around a little before deciding who does the work.  

Regards,

John