Vehicles

• If possible, avoid driving as ash is harmful to vehicles, the roads may be slippery and driving suspends ash into the air that causes low visibility and may be harmful or irritating to others.
• If driving is crucial, drive slowly, use headlights and ample windscreen fluid. Using wipers on dry ash may scratch the windscreen. In heavier ashfall driving should only be undertaken in an emergency. Use water bottles and a cloth to clean the windscreen as required, this may be every few tens of meters.
• Change oil and oil filters frequently (every 50-100 miles (80-160 km) in heavy dust; every 500-1000 miles (800-1600 km) in light dust).
• Do not drive without an air filter. If you cannot change it, clean it by blowing air from the inside out. Do not change it until you notice a loss of power to the engine, as a dirty filter is more effective than a clean one.
• Cleaning your car - clean ash from inside your engine, trunk/boot and spare tire storage area as well as the seating area. Brushing ash off the car can cause scratching.
• Have a service garage clean wheel brake assemblies every 50-100 miles (80-160 km) for very severe road conditions, or every 200-500 (320-800 km) miles for heavy dust conditions.
• The brake assemblies should be cleaned with compressed air.
• Have a service garage clean alternators with compressed air after heavy accumulation, every 500 to 1000 miles (800-1600 km), or after severe dust exposure.
• Clean the vehicle, including the engine, radiator and other essential parts daily and if necessary, use water to flush the ash.
• Wash the engine compartment with a garden hose or steam cleaner. Be sure to seal off air intakes and electrical components before cleaning.

Damage to vehicles

Volcanic ash can infiltrate nearly every opening and abrade or scratch most surfaces, especially between moving parts of vehicles. Ash particles easily clog air-filtration systems, which can lead to overheating and engine failure. Small concentrations of ash particles inside an engine can cause extra engine wear. Transmissions experience extra wear after ingesting minute ash particles.

Seals on hydraulic components may wear out faster than usual, and brakes and brake assemblies are especially vulnerable to abrasion and clogging from ash. Trucks used to transport ash to disposal sites and other vehicles subjected to heavy ash exposure may require constant brake attention.

Ash caught between windshields and wiper blades will scratch and permanently mark the windshield glass, and windows are susceptible to scratching each time they are raised, lowered, and cleaned. Corrosion of paintwork and exterior fittings may also result where ash is in contact with the exterior.

Special maintenance

Strategies for reducing the effects of ash on vehicles involve frequent oil changes, cleaning or replacing air filters often, using air pressure (< 30 lbs/in²) to blow ash from electrical equipment and other essential engine components (for example, alternator, starter, wiper motor, and radiator), and frequently cleaning vehicles with water to wash away the ash. During such cleanup, care should be taken to ensure the ash does not enter a wastewater or drain-water system.

The list below provides some protective measures for vehicles driven in ashy conditions based on the experience of the 18 May 1980 eruption of Mount St. Helens. Vehicle owners and operators are encouraged to obtain maintenance manuals and manufacturers' recommendations that may be available for operating vehicles in ashy or dusty conditions. For example, in June 1980 General Motors Corporation issued a public service announcement to drivers in ash fallout areas from the Mt. St. Helens eruption.

Suggested measures for reducing effects of ash on vehicles:

Driving

• Avoid driving in heavy ash conditions unless absolutely required.
• When required to drive in ashy conditions keep speed below 55 kilometers per hour (35 mph) or lower. Do not follow too close to the car ahead, and use headlights on low beam.

Oil change and air filters

• Change oil often. In very dense ash conditions change oil at 80-160 kilometers (50-100 mi) intervals. In light ash conditions change oil at 800-1,600 kilometers (500-1000 mi) intervals. Lubricate all chassis components at each oil change.
• Clean air filters by back-flushing filter paper with compressed air (30 lbs/in²). Caution—blow element from inside (clean side) to outside (dirty side). DO NOT strike filters against anything. Air clean only. If unsure, have a qualified mechanic perform the air filter service. Inspect filters for dents or torn paper.
  Clean the inside of filters and the filter cover with damp cloth before reinstalling filter.
• Commercial truck filters can be installed to increase the filtering capacity of the cleaner. This would be beneficial for vehicles operating continuously in extreme dust conditions.
• Air filter restriction gauges can be installed by qualified mechanics. The gauge will tell you when your air filter requires servicing in order to avoid over-servicing.
• DO NOT install hose from carburetor air intake (air clean) to inside of car. Outside dust and ash will be drawn into vehicle.
• Rags, or any other intended filtering material, should not be placed over the carburetor inlet inside the air cleaner element; serious damage to the engine and/or loss of vehicle control may result.

Outside vents

• Cover passenger compartment vent inlet (located at base of wind-shield and usually under hood) with thick, loosely woven felt-type material to filter air into vehicles. With vent filter in place, keep heater blower high. Blower will slightly pressurize inside of vehicle and keep dust from entering through body gaps or holes. If a vent filter is NOT installed, keep air conditioner and heater blowers off.
• Utilize 'internal-only' circulation option available on many modern cars.

Cleaning

• Have a service garage clean wheel brake assemblies every 80-160 km (50-100 mi) for very severe road conditions, or every 800-1600 km (200-500 mi) for heavy dust conditions. The brake assemblies should be cleaned with compressed air.
• Have service garage clean alternators winding with compressed air after heavy accumulation or every 500 to 1000 miles or after severe dust exposure.
• Clean the vehicle, including the engine, radiator, and other essential parts daily, if necessary, using water to flush the ash. Wash the engine compartment with a garden hose or steam cleaner. Be sure to seal off air intakes and electrical components before cleaning.

Notes
After running vehicles in heavy concentrations of ash, the equipment life of properly serviced vehicles, as outlined above, may be somewhat reduced, but the equipment probably will not have catastrophic failures. Failures attributable only to ashfall can be expected to occur within 30 days following the exposure period. Modified from, FEMA, 1984 - note, guidance may be slightly out of date with respect to modern automobile technology.