To change transfer case oil, locate the transfer case, position it so you can look into it, locate the fill plug, and remove it with a hex driver. You can find the transfer case in the center of the undercarriage. No oil drains once the fill plug is removed.
Next, take a drain pan with enough room for at least 2 quarts of oil, and place it directly under the transfer case. Find the drain plug under the fill plug, and remove it carefully with a hex driver to avoid oil spillage. Once the plug has been completely loosened, remove it quickly, and allow the oil to drain into the oil pan. Oil takes at least five minutes to drain completely from the transfer case.
Once the oil has drained, use the hex driver to tighten the drain plug back into place. Using a vacuum oil pump, take the ATF oil, and fill the transfer case. The case is full once oil begins dripping out of the fill hole. When this happens, use the hex driver to tighten the fill plug again. Each plug must line up to prevent cross-threading. Be cautious when tightening the plugs, as over-tightening can strip the threads.