Do you mean 3 kg/cm? At 3000RPM, when fully warm it should be at 6. When IDLING at fully warm it could drop as low as 3.
If you're getting those readings at 7200RPM, do not drive the car! Replace the sending unit (at the base of the oil filter, a large brass object) and drive again. If it still reads the same, replace the gauge. If it still reads the same after all of that, you have some serious problems with the oil-pump...
If you're getting those readings at 7200RPM, do not drive the car! Replace the sending unit (at the base of the oil filter, a large brass object) and drive again. If it still reads the same, replace the gauge. If it still reads the same after all of that, you have some serious problems with the oil-pump...