The engine oil drain plug on a 2002 GMC Sonoma is located on the
bottom of the oil pan. The oil pan is the large, somewhat flat metal part underneath the engine. You'll need to get under the truck to access it. It's usually near the front of the oil pan, but its exact position might vary slightly depending on the engine (4.3L V6 or 2.2L 4-cylinder).
Important Safety Note: Before attempting to change your oil, make sure the engine is completely cool to prevent burns. Consult your owner's manual for the correct oil type and capacity for your specific Sonoma engine. Also, be prepared to properly dispose of used oil.
