1999 Chevrolet S10 Pickup Owner's Manual - Page 263

yellowblue When the differential is cold, add enough lubricant to raise the level to 1/2 inch (12 mm) below the filler plug hole. When the differential is at operating temperature (warm), add enough lubricant to raise the level to the bottom of the filler plug hole. What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See "Recommended Fluids and Lubricants" in the Index. Radiator Pressure Cap NOTICE: Your radiator cap is a 15 psi (105 kPa) pressure-type cap and must be tightly installed to prevent coolant loss and possible engine damage from overheating. Be sure the arrows on the cap line up with the overflow tube on the radiator filler neck. 6-25