1996 Ford Bronco Owner's Manual - Page 291

NOTE: Idling the engine for extended periods will accumulate more hours of use on your vehicles than is actually indicated by the mileage odometer. Consequently, the odometer reading can be often misleading when determining the right time to change your engine oil and filter. If you are using your Ford vehicle in a manner which allows it to remain stationary while the engine is running for long periods (door to door delivery, taxi, police, power/utility company trucks, or similar duty), then Ford recommends you increase the frequency of oil and filter changes to an interval equivalent to 200 ENGINE HOURS of use. Since most vehicles are not equipped with hourmeters, it may be necessary for you to approximate your idle time and plan oil/filter changes accordingly. Refer to the Maintenance Schedule and Record booklet for additional information. NOTE: Always dispose of used automotive fluids in a responsible manner. Follow your community's standards for disposing of these types of fluids. Call your local recycling center to find out about recycling automotive fluids. RWARNING Continuous contact with USED motor oil has caused cancer in laboratory mice. Protect your skin by washing with soap and water. 294