91 Mercury Capri - oil pressure fluctuating with RPM


What is the cause/repair for oil pressure that fluctuates with RPM? Oil pressure is high when first start the car, then begins to fluctuate with RPM after about 2 miles. When idling, it gets really close to the low red zone.


How long as the oil been in there? Is it an oil specified by the manufacturer?

It is not unusual for oil pressure to vary with the RPM. Does the gauge have numbers? What range is it moving through?


The oil was changed last week to Valvoline 10W40. Previously it had 10W30. The 10W40 was recommended by Napa because the 10W30 was too thin. There are no numbers on the gauge, just a line at the top labeled H, a line toward the bottom, a small space, red zone and a low line labeled L. It is at H when starting then fluctuates between 3/4 point and the line above the red zone. After driving about 12 miles it starts to go below the line in the space before the red zone when idling at a traffic light. It doesn’t look like the oil pump was changed during the rebuild 11/2001. The pressure started fluctuating in the last year.