2007 Chevrolet Colorado Owner's Manual - Page 370

If the level is below the bottom of the filler plug hole, located on the front axle, you may need to add some lubricant. 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. Bulb Replacement For the proper type of replacement bulbs, see Replacement Bulbs on page 374. For any bulb changing procedure not listed in this section, contact your dealer. Halogen Bulbs What to Use See Recommended Fluids and Lubricants on page 455 to determine what kind of lubricant to use. {CAUTION: Halogen bulbs have pressurized gas inside and can burst if you drop or scratch the bulb. You or others could be injured. Be sure to read and follow the instructions on the bulb package. 370