My oil pressure gauge was functioning perfectly well but I noticed the occasional oil warning light flashing and the gauge itself dropped ever so slightly causing the light to flash. This was intermittent. I had the oil sender unit replaced (oil pressure checked and was ok) but just after I picked it up the gauge started working like a windscreen wiper with the corresponding warning light flashing. It settles down when it gets warm, but will still flash occasionally. In a further development tonight I noticed that the fan stayed on and I got 3 groups of two beeps from somewhere under the dash board (foot-well area) at intermittent periods. Also when I stopped the car and tried to restart it again it didn't want to play ball but eventually started on the second attempt which is totally out of character. There are no strange noises from the engine (apart from the vibration of the fan) and no warning lights apart from the intermittent oil pressure warning light already mentioned. Oil is up to the max and a new filter has been fitted. Any comments/advice welcome!