1994 GMC Sonoma Owner's Manual - Page 263

Engine Control Module System This system has an oxygen (02) sensor that helps keep your engine's air-fuel mixture at a proper level. Use only unleaded fuel in your vehicle. If you use leaded fuel, you could damage your oxygen (02) sensor and affect your vehicle's emissions. Loading Your Vehicle The CertificatiodTirelabel is found on the driver's door lock pillar. The label shows the size of your original tires and the inflation pressures needed to obtain the gross weight capacity of your vehicle. This is called the GVWR (Gross Vehicle Weight Rating). The GVWR includes the weight of the vehicle, all occupants, fuel and cargo. The Certification/Tirelabel also tells you the maximum weights for the front and rear axles, called Gross Axle Weight Rating (GAWR). To find out the actual loads on your front and rear axles, you need to go to a weigh station and weigh your vehicle. Your dealer can help you with this. Be sure to spread out your load equally on both sides of the centerline. Never exceed the GVWR for your vehicle, or theGross Axle Weight Rating (GAWR) for eitherthe front orrear axle. And, if you do have a heavy load, you should spread it out.