Oil changes on a 1999 Chevy Silverado Z71 should be accomplished every 3,000 miles to prevent the formation of sludge. Oil cannot be destroyed other than burning, although it can become severely contaminated. When the engine is cold, the pistons and rings contract, creating a poor seal until they have warmed up and expanded. This allows combustion gases to bypass the rings and enter the crankcase and mix with the oil. This and the condensation on the inside of a cold engine result in ever-increasing contamination. These factors coupled with the breakdown of additives to the oil create sludge if the oil is not changed regularly. This sludge blocks the oil flow from the cylinder head to the oil pan.
Instructions
- 1
Raise the truck with the floor jack and place jack stands under the frame. Lower the truck so it rests on the stands. Place the oil drain pan under the oil pan and remove the drain plug in the pan using a wrench. Allow the oil to drain.
2Install the drain plug in the oil pan and tighten the plug snugly. Do not overtighten it as the threads will strip. Remove the oil filter on the driver's side rear of the engine using an oil filter wrench. Make sure the O-ring comes off with the oil filter.
3Spread a little oil on the O-ring on the new filter and thread it on as tight as possible by hand. Do not use the filter wrench to tighten it.
4Lower the truck. Open the hood and remove the oil filler cap. Fill the engine with 6 quarts of oil and replace the cap. Pull the dipstick, wipe it off and reinsert it. Pull the dipstick and check the oil level.
