Question: I'm a newbie in the oldtimer scene, recently bought a Bentley Eight 1987 with 'things to do'. When I start the car from cold the oil pressure needle is in the bottom part of the solid with block. After driving for approx 20 minutes the needle drops to them middle between the solid line and the 'low' indication. If a stop a traffic light and idle the needle drops further to almost the 'low' indication but when I put the gear in 'P', still idling, the needle rises to well in the middle of the solid white block. It stays there for approx 20 minutes and starts dropping again. What could be wrong?

Answer: This sounds like it could be a faulty gauge or sender. We would also Suggest doing an oil and filter change as a starting point.