I own a Fiat Panda 1.1 Active. I recently had an oil change about 3 weeks ago and since last week I have noticed a ticking noise coming from the engine. It only really happens on starting the engine after applying some acceleration. Once you've driven it after a couple of miles and pull over the noise disappears although every so often I think I hear it, but I'm not 100% sure. I was wondering if it could be a hydraulic tappet problem?

The garage where I had it serviced said they have used the correct grade of oil in accordance with the manufacturer's specifications and have recently put an oil additive and said to me to give it a few weeks to work its way through the engine. However I was wondering whether these tappets could be adjusted as it sounds like the noise is coming towards the bottom of the engine and not near the top. Any advice would be great.