1994 GMC Sonoma Owner's Manual - Page 232

Used oil can be a real threat to the environment. If you change your own oil, be sure to drain all free-flowing oil from the filter before disposal. Don't ever disposeof oil by putting it in the trash, pouring it on the ground, into sewers, or into streams or bodies of water. Instead, recycle it by taking it to a place that collects used oil. If you have a problem properly disposing of your used oil, ask your dealer, a service station or a local recycling center for help. Air Cleaner To remove the round air cleaner filter for the 4.3L (VIN Z) engine, turn the wing nuts to the left. Remove the cover and change the filter. Care should be taken during reassembly to ensure that the cover is on straight and the wingnuts properly tightened. To remove the square air cleaner filter for the 2.2L (VIN'4) and the 4.3L (VIN W) engines, open both clamps and push the rear of the air cleaner back toward the rear of the engine compartment to change the filter. 6-14