1995 GMC Sonoma Owner's Manual - Page 257

Lock Cylinders To be sure your locks operate properly, they must be lubricated. Refer to the Maintenance Schedule to determine how often to lubricate them and what type of lubricant to use. You should not use penetrating oils because they could wash out the factory installed lubricant and causethe lock to bind. De-icers which contain alcohol could alsowash away the lubricant, so be sure to lubricate the lock after using a de-icer of this type. Exhaust System To help prevent damage to your exhaust system,do not continue to drive your vehicleif you notice: Engine misfiring Loss of performance Exhaust system components hanging lower than normal. Loud exhaust system noises. Other unusual operating conditions Have your engineand exhaust system serviced regularly. Three- Way Catalytic Converter Your vehicle's three-way catalytic converteris designed to reduce the pollutants in your vehicle's exhaust. Use only unleaded fuel in your vehicle. If you use leaded fuel,you could damage your three-way catalytic converter and other engine components. Engine Control Module System This system hasan oxygen (02) sensor that helps keep your engine's air-fuel mixture at a properlevel. 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. Malfunction Indicator Lamp (SERVICE ENGlNE SOON) This light on your instrument panel lets you know when your emission system needs service. See "Malfunction Indicator Lamp" in the Index. 6-39