My YJ Has About 55 PSI At First Cold Start Up,But Then It's All Down Hill. After Driving On The Highway For A Bit And Reaching Operating Temperature It Will Eventually Drop To 20 PSI At 6Omph. Once I Get Off The Highway And Come To A Stop The Pressure Goes Down To 0. Even Though It's At 0 The Motor Still Sounds And Runs Fine. I Can't Hear The Lifters Grinding Or Anything. It Ticks Once In A While, But It Always Did. My Gauge Is Fine. I Replaced The Electrical Sender Once And Then Switched To A Mechanical Gauge. Both Read Exactly The Same. Could This Be Caused By A Leaking Timing Cover Gasket And Pulley Seal? Mine Do Leak. Oil Pump Has Less Than 5000 Miles On It. Any Ideas?