I've had my A4 1.8T off the road for a few weeks whilst I did some jobs on it. One of the jobs was water pump and timing belt. I started the car for the first time in four weeks today and found that the top end is now noisy (it wasn't noisy before the lay-up). I let the engine idle for about 15 minutes and it came up to temperature (90C), although I noticed that the oil temperature didn't rise above 60C. The noise stayed the same throughout this period.

The noise sounds similar to what the hydraulic tappets of my Mk1 MX-5 make if I don't use it for a few weeks, but they go quiet after a few seconds.

If the noise is caused by the oil draining out of the tappets, would you expect 15 minutes of iding to refill them? What oil temperature would you typically expect?

Thanks.