mal thory

I have the same problem, with the same car at 97.000 miles. I took it to a so called engine specialist and they changed the tappets. No difference. They then did an oil pressure test and found the pressure was low as the engine warmed up. Their only suggestion was that the big ends or the main bearings were worn. Research on the net may suggest that it is the pressure relief valve in the oil pump. Without spending a fortune I think the only answer is to live with it.Hope this helps a bit.