2003 GMC Sierra 1500 Pickup Owner's Manual - Page 202

Oil Pressure Gage A reading in the low pressure zone maybe caused by a dangerously lowoil levelor some otherproblem causing low oil pressure. Check youroil as soon as possible. See Oil Pressure Low under DIC Warnings and Messages on page 3-60 -7d Engine Oil on page 5- 17. United States Canada Don't keep driving if the oil pressure is low. If you do, your engine can becomeso hot that it catches fire. You or others could be burned. Check your oil as soon as possible and have your vehicle serviced. The oil pressure gage shows the engine oil pressure in psi (pounds per square inch) when the engine is running. Canadian vehicles indicate pressure in kPa (kilopascals). Oil pressure may vary with engine speed, outside temperature and oil viscosity, but readings above the low pressure zone indicate the normal operating range. Notice: Damage to your engine from neglected oil problems can be costly and not covered by is your warranty. 3-47