1998 GMC Sonoma Owner's Manual - Page 265

If none of them is true, use the long trip/highway maintenance schedule. Change the oil and filter every 7,500 miles (12 500 km) or 12 months -- whichever occurs first. Driving a vehicle with a fully warmed engine under highway conditions causes engineoil to break down slower. What to Do with Used Oil Did you know that used engine oil contains certain elements that may be unhealthy for your skin and could even cause cancer'? Don't let used oil stay on your skin for very long. Clean your skin and nails with soap and water, or agood hand cleaner. Wash or properly throw away clothing or rags containing used engine oil. (See the manufacturer's warnings about the use and disposal of oil products.) 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 forhelp. Remote Oil Filter (Four-wheel Drive) The access door for remote oil filter is in the steering the linkage shield assembly located under the radiator support. Twist the screw to unlock or lock the door. Make sure if you open the door, it is securely closed when you are finished. 6-15