I have just bought a disco 3.5 v8i auto, after a long run when the engine has been warm and when i stop the car and leave it in drive the oil pressure light comes on but then dissapears when i set off or put it in nuetral, is this a common fault. Does anyone know what kind of resistance i should get through the sensor or another way of checking the pressure sensor. I have also heard of the oil pumps failing on v8's can anyone reccomend a good oil pressure gauge and fitting kit to check and monitor the pressure.