last week I noticed that the oil pressure was reading around 20 when it usually holds at around 40. Over the past week, it has been gradually reading lower and lower. Today I drove 200 miles, stopped for gas, restarted the jeep and the gauge stayed hovering at zero with the check gauges light on. Made it the remaining 15 miles home with no problems. Is it the gauge? Can I drive it to work tomorrow? Should I just replace the pump? (97 TJ).