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  • Ten Easy Ways to Save at the Gas Pump

    Posted on July 15th, 2008 ninarussin

    By Nina Russin

    Associated Press: Hugh E. Gentry

    Associated Press: Hugh E. Gentry

    New hybrids and clean diesel cars on the market are a great way for car buyers to stretch their gas dollars. But what about drivers who need to stay in their current vehicles? The following routine maintenance procedures will help any car or truck owner improve their overall fuel economy.

    1. Check tire pressures at least once a week; more often if there are large temperature fluctuations. Under-inflated tires reduce fuel economy, and the tires will wear unevenly. If the car is running on original equipment tires, the owner’s manual should have recommended tire pressures. If not, look for a sticker on the driver’s side door sill, or inside the glove box.

    Never inflate tires to the maximum pressures listed on the sidewalls. Most gas station air pumps have pressure gauges, but it’s a good idea to keep one in the car just in case.

    2. Change the oil every three thousand miles. Oil lubricates the moving parts inside the engine. It becomes contaminated from air-born dirt entering the engine, and it also breaks down from engine heat. The owner’s manual will list the correct viscosity of oil to use. Some manufacturers recommend changing oil viscosity semi-annually, to adjust for seasonal temperature changes. Synthetic oil costs a little more, but it can make a big difference in high performance cars, where higher engine temperatures can cause oil to break down more quickly .

    3. Check the air and fuel filters at every oil change. The purpose of the filters is to keep pollutants and particulates out of the engine. But if they become clogged, they restrict air and fuel flow into the engine, so it can’t run as efficiently. The car’s on-board computer can’t “see” dirt in the filters, so it won’t make adjustments to compensate. The same applies to the throttle body housing. An electronic sensor monitors throttle valve position, but it doesn’t look at dirt buildup around the valve. Have the throttle body housing inspected as part of a preventative maintenance tune-up, once every 30,000 miles.

    4. Rotate the tires every other oil change, and have wheel alignment checked every 25,000 miles. Wheels and tires are like feet and running shoes: when they don’t track straight, they lose efficiency. Wheels out of alignment also cause premature wear on suspension parts, similar to the way overpronation can cause tendonitis. Rotating the tires every five to six thousand miles will extend tire life even further.

    5. Have a preventative maintenance tune-up every thirty thousand miles. Today’s cars have fewer moving parts than older cars. Whereas semi-annual tune-ups used to consist of changing mechanical parts that wore out, today’s tune-ups monitor for performance problems. This includes base timing, engine compression, spark plug erosion, and dirt on the fuel injector tips, none of which are monitored by the car’s computer. While the car may run up to 100,000 miles without a tune-up, gas mileage will suffer. If the car is off warranty, look for a good independent shop where the technicians are ASE certified. ASE certification requires technicians to have several years of field experience, and be well versed in new automotive technology.

    6. Replace the oxygen sensor every 60,000 miles. The oxygen sensor monitors the exhaust stream to help the computer determine the proper ratio of gasoline to air going into the engine. These sensors are potentiometers: they rarely fail completely, but they tend to get sluggish over time. When the sensor slows down, the on-board computer can’t respond as quickly to changes in engine load, impacting the car’s overall performance and hurting gas mileage.

    7. Have the timing belt checked at 60,000 miles, and replace it if necessary. Over time, the cogs on the belt get rounded off, so the belt can shift when the engine advances and retards timing. Timing out of adjustment reduces gas mileage. If the timing belt breaks, be prepared to be stuck on the side of the road. In some cases a broken timing belt can cause the engine valves to play tag with the pistons: the result, a blown engine.

    8. Service the air conditioner every couple of years on a newer car; annually on an older one. Believe it or not, using the air conditioner at highway speeds is more fuel efficient than driving with the windows down, because it reduces aerodymanic drag. Check a noisy compressor as well: if the bearings inside freeze up, it will wear out the compressor belt and put additional load on the engine.

    9. Service the cooling system every two years: The term, “cooling system,” is deceptive, because the system also helps the engine to reach operating temperature in cold weather. The period before a car reaches operating temperature is called “open loop.” During those couple of minutes (or more on older cars) the computer doesn’t monitor the gasoline and air going into the engine. The longer it takes a car to reach operating temperature, the more fuel economy suffers. Antifreeze loses its cooling and lubricating properties over time, so it needs to be flushed out and refilled.

    10. Wash your car regularly. Engineers spend hours in the wind tunnel trying to minimize a new vehicle’s coefficient of drag. They don’t test dirty cars, because dirt increases aerodymanic drag. Washing and waxing the car on a regular basis stretches gas mileage, and protects the paint from sun damage, road salt, and acid rain.

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