wouldn't definitely cure your problem, assuming that the noise is a tappet. However, in the past, I used it twice on two different Vauxhalls, both fitted with 8v petrol engines, hydraulic tappets, in each case one or two tappets really rattly unless you revved the engine really hard, then they stopped doing it. Ran the engine flush through with the oil change, and the problem went away. Couldn't swear hand on heart that it was the engine flush that cured it, or whether it was the oil change. Back then, I was changing the oil on these cars every 5000 miles, so it was unlikely to be oil based gunk sticking them up.
There are quite a few engine flushes available, have a look along the shelf in Halfords. It's basically and solvent and thin oil mix which you put in the oil filler, then run the engine on fast idle for 20 mins or so, then do the oil and filter change straight away while the oil is red hot. This way all the crud drains out of the engine, the hotter the oil, the thinner it becomes, and so drains more completely.
Then change the filter and oil, and away you go.
In the past, on older less sophisticated engines, I used to use a post oil change treatment, such as slick 50. However, things (engines) have changed a lot since then, and now I wouldn't dare use it in a modern engine with finer tolerances, turbo etc. I just rely on good old fashioned regular oil changes, and use an engine flush every 3rd or 4th oil change.
