Vehicle Mileage Maintenance
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Vehicle Mileage Maintenance

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A mere 0.7 of a mile does not sound like much, it is about 3,700 feet, or less than one-third the distance around Daytona International Speedway.

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On average, the U.S. population of vehicles will get 20 miles per gallon (including light trucks and passenger vehicles). A 0.7 of a mile improvement represents only a 3.5 percent improvement. But, this would represent a yearly savings of $17 billion in fuel if the cost of a gallon of gas in the U.S. stays around $3.00. It can be difficult for your customers to grasp how a poorly performing vehicle can use more fuel. Most people assume that if their vehicle is not performing properly, it must be getting less fuel. The opposite is true. When a vehicle is not performing properly, the driver will consciously, or unconsciously, depress the gas pedal further to achieve the same performance. This happens regardless even if the driver is pulling away from a light or cruising on the freeway trying to keep a constant speed. Also, the loss of performance may be so gradual that the driver does not notice that there is a problem.

The very small improvement of 3.5 percent can be achieved through simple maintenance that often goes unperformed or unrecommended by automotive repair shops. It is simple items like spark plugs, filters and engine sensors that can yield these improvements.Gas mileage can be improved by 1 to 2 percent by just using the manufacturer’s recommended grade of motor oil and changing it at recommended intervals. When oil is too heavy of a weight, the oil pump requires more power from the engine to pump the oil.

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For example, using 10W-30 motor oil in an engine designed to use 5W-30, can lower gas mileage by 1 to 2 percent. Using 5W-30 in an engine designed for 5W-20 can lower the gas mileage by 1 to 1.5 percent. Also, a restricted oil filter can cause the oil pump to work even harder. A 2 percent gain in fuel economy can mean a savings of $37.50 over a year’s time.Replacing a clogged air filter can improve a vehicle’s gas mileage by as much as 10 percent. Engines use up to 14,000 gallons of air for each gallon of gas. A restricted air filter can block the air and cause the motor to run too rich. Having the air filter replaced can save a customer an average of $202.50 a year.

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Replacing worn spark plugs can result in a 3 to 4 percent increase in fuel economy. Spark plugs undergo changes that increase the required ignition voltage. When the required voltage reaches a level that can no longer be compensated for by the voltage reserve, the result is misfiring. Spark plug replacement could mean savings of $75 to $90 over a year at the pumps.

Replacing a worn out or defective oxygen sensor can result in a 15 percent gain in fuel economy. As an oxygen sensor ages, it becomes slower to react and produces inaccurate readings. This can mean a fuel mixture that is too rich. Also, heated oxygen sensors may not warm up as fast as they did when they were new. This could lead to increased start up emissions and fuel consumption. Replacing a defective oxygen sensor can mean a fuel savings of $295 over the next year.

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Other engine sensors, like mass air flow and throttle position sensors, can impact fuel mileage between 10 to 25 percent. These repairs may seem like a lot of money to the customer up front. But, when weighed against the savings of $202 to $450 at the pump over a year, the choice is clear.According to the Car Care Council, about 17 percent of the vehicles on the roads have gas caps that are either damaged, loose or are missing altogether, causing 147 million gallons of gas to vaporize every year. This will cost consumers $436 million if gas prices stay above $3.00 for the next year. By replacing a broken or defective gas cap, you could improve a customers fuel mileage by 0.5 percent in some cases.Proper alignment is critical for fuel-efficient driving. If a vehicle is driven 12,000 miles and the wheel’s toe is tilted inward by 0.34 degrees out of specification, by the end of the year the tires have been dragged sideways for 68 miles. This not only wastes gas, but it shortens the life of the tires.Weighing the cost of any repair against the fuel savings is only part of the equation.

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If a customer turns down a repair in favor of living with poor fuel economy, remind them that the repair will pay off in other ways.First, repairing one component can extend the life of other components. If a fuel filter is restricted, the fuel pump will have to work harder to deliver the right amount of fuel to the engine. This can shorten its life dramatically and cost the customer more money in the long term.Second, having a properly functioning vehicle insures the value of their investment. And, in a world where savings accounts pay less than 2 percent interest and most mutual funds return only 4 percent, investment in a vehicle can yield better dividends in the short term and long term.

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IF A BATTERY KEEPS RUNNING DOWN, IS IT A BAD BATTERY OR A CHARGING SYSTEM PROBLEM?
It could be either – or neither. Diagnosis is the key to isolating the fault. Unfortunately, batteries and alternators are sometimes replaced unnecessarily because the problem was misdiagnosed.The first thing that should be checked is the battery. Various types of testers are available for this purpose. A traditional load tester requires the battery to be fully recharged before it can be tested, but some of the newer electronic testers can test batteries that are run down. The tester will reveal whether or not the battery can deliver the required amps.Average battery life is only about four years in most areas of the country, and only about three years in the hottest areas such as Arizona and New Mexico. Heat and vibration are a battery’s worst enemies. Heat can damage plates and increase the rate at which water evaporates from the cells, allowing plates to dry out. Vibration can cause cracks and shorts in plates and internal connections.If a battery won’t accept a charge, sometimes reducing the charging rate and leaving it on the charger for a long period of time (4 to 6 amps for 24 hours) will revive it. But in most cases, the battery will probably have to be replaced.

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WITH TODAY’S LONG-LIFE SPARK PLUGS, ARE PLUG REPLACEMENTS A THING OF THE PAST?
Not yet, though some of your customers may think so. Many new vehicles have spark plugs with 100,000 mile replacement intervals, most older vehicles have plugs that still need to be replaced periodically for preventive maintenance. And any spark plug, regardless of how long it is supposed to last, may become fouled or fail for a variety of reasons.The spark plugs are still one of the most important maintenance items under the hood – just look at your sales numbers. No spark means no combustion, wasted energy, increased emissions, loss of performance, idle roughness, hesitation, hard starting – and possibly even a no start if all of the plugs are affected.WHEN SHOULD A CATALYTIC CONVERTER BE REPLACED?
When it is no longer reducing pollutants in the exhaust, when it is plugged or when it is leaking or damaged.Contamination is one reason why converter efficiency drops off over time. As a converter ages, the catalyst gets “tired” because of a gradual accumulation of contaminants on its surface. The process can be accelerated by the accumulation of phosphorus deposits from oil burning or silicone deposits from internal coolant leaks. As the contaminants build up, hydrocarbons (HC), carbon dioxide (CO) and NOx emissions begin to rise. There is no effect on engine performance.The converter may become plugged if unburned fuel enters the exhaust. The converter acts like an afterburner to get rid of HC, and if there’s too much HC in the exhaust, it can cause the converter to overheat and melt. The result may be a partial or complete obstruction depending on how much damage is done to the catalyst.Heat, corrosion and vibration also take a toll on the converter as a vehicle accumulates miles. Most OEM converters are designed to go 100,000-plus miles, but after a decade of use, thousands of thermal cycles and zillions of cubic feet of hot corrosive gases blasting through its innards, the stainless shell may crack or rust through.’

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Q: What are the symptoms of a bad O2 sensor?A. Symptoms of a sluggish or failed O2 sensor include:

Failed emissions test (high CO and/or HC typically);

Damaged catalytic converter (from an over rich fuel mixture);

Poor fuel mileage (caused by over rich fuel mixture);

Fouled spark plugs (caused by over rich fuel mixture);

Runs rough at idle; and

Sluggish performance.If testing reveals the O2 sensor is not performing up to specifications, it must be replaced to restore proper engine control, fuel economy, emissions and performance.Q: SPARK PLUG WIRES
Why should I replace my spark plug wires if they only cause problems when it rains? Spark plug wires should be replaced regardless because they could cause misfires that the driver my not detect.Plug wires can deteriorate with age causing misfires, hard starting and poor performance. Wires should be replaced if the boots or terminals are loose, damaged or corroded, if the wires are cracked or sparking or if their internal resistance exceeds specifications.The spark plug wires (ignition cables) carry high voltage from the coil or distributor to the spark plug. Some wires have carbon-impregnated fiberglass strands inside to carry the voltage, while others have spiral-wound “mag” wire. There is one plug wire for each spark plug, and the wires can be replaced individually or in sets.As a rule, the whole set of wires should be replaced if one or more of the old wires are in poor condition. Wires should be installed one at a time so as not to mix up their firing order.

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DO FUEL FILTERS STILL NEED TO BE REPLACED?
Not as often as they once did, but eventually most fuel filters will become saturated with debris and plug up. A plugged filter will restrict the flow of fuel to the engine, causing performance problems such as lack of high-speed power, stalling and hard starting. If the filter has a built-in bypass valve, plugging will open the bypass and allow unfiltered fuel to flow to the injectors or carburetor that can cause additional problems if these parts also become clogged with debris.Clean fuel is especially important with fuel injection because particles of rust and sediment from the fuel tank can clog the injector inlet screens. And if debris gets inside the injector, it can wear or jam the pintle valve and seat.To minimize the risk of plugging, recommend replacing the fuel filter every 25,000 to 30,000 miles for preventive maintenance. Additional items that may also be needed include fuel hose and clamps.

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CAN AN AIR FILTER MAKE A DIFFERENCE IN FUEL ECONOMY?
Roughly 14,000 gallons of air are needed for today’s cars and trucks to efficiently burn one gallon of gasoline. Dirt equivalent to the size of two aspirin tablets within that air will cause the same amount of wear as 75,000 miles of normal driving. With that in mind, it’s easy to see that these filters are an engine’s first line of defense against dirt and the damage it causes.Without a quality air filter, dirt, road grit and other debris can “sand blast” internal engine parts, carburetors and fuel injectors.With either style air filter, a duct directs outside air to the filter. Once the air is filtered it passes on to the fuel system and combustion chambers.

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