pressure in chevy lumina sedan 1995

These are generic specs, no particular engine or model year. 20--30 psi at idle rpms. 40- -60 psi at highway rpms. An old rule of thumb, that I saw listed, somewhere, minimum 10 psi for every thousand rpms. Of course if your vehicle is a high mileage engine, the specs may differ. Like I said, these are generic specs.