Some drivers may still remember when a car's engine needed a complete tune up every 10,000 miles, but those times have changed. Today, there are several models being advertised as needing a "tune up" every 100,000 miles. The claims may lead you to ask a couple of questions: First, is this boast true? Secondly, if it is, how is that possible?
"Car manufacturers can claim 100,000 mile tune up intervals for a number of reasons involving spark plugs," says Paul Coccari, Autolite spark plug product manager for Allied Signal Automotive Aftermarket. "For one thing, some people believe that a tune up has evolved to only mean a spark plug change. Also, sophisticated engine designs with extremely precise fuel injection systems are less likely to foul spark plugs, leaded gasoline isn't available and we're making better spark plugs."
Coping Under Fire
Autolite's Coccari says a lot has changed in spark plug design since the days of the 10,000 mile plug change.
"One thing engineers realized some time ago was the necessity of conducting heat away from the spark plug's tips," Coccari states. "Since copper is a great conductor of heat, better spark plugs have used copper cores in their center electrodes for years."
But to get maximum life and performance out of a spark plug, Coccari says it was also necessary to improve the firing surfaces themselves. Metallurgical research showed that a high nickel chromium alloy did a good job of resisting the forces trying to damage the plug. In fact, the high nickel chrome electrodes resisted heat and erosion enough that the better standard grade spark plugs could maintain their gap setting for at least two years or 30,000 miles.
"However, engineering is often a matter of improving on what's already good," Coccari explains. "In addition, consumers are always looking for something better and that's how double platinum spark plugs have evolved."
Double platinum spark plugs have small platinum discs on the firing surfaces of both their center and side electrodes. The platinum does a superlative job of resisting erosion, so that the gap of the electrode stays virtually as set by the installer for as long as 100,000 miles.
The platinum firing surfaces don't just promote longevity, they also allow for improved performance. Because platinum resists erosion, it allows the use of a narrowed firing electrode. A variation on what's known as "fine wine" spark plug design, the double platinum plug's smaller tip won't block the growth of flame the way thicker electrodes do. And the faster the flame created by the firing of the spark plug can be spread, the better the engine can perform.
So, What's A Tune - Up?
The definition of a tune up has been evolving as cars have gotten more sophisticated. At one time, a tune up included setting idle speed, ignition timing and valve lash, which are all set automatically on many modern cars. Most modern engines don't use ignition distributors any more, so the distributor cap and rotor are long gone.
However, even with these changes, this doesn't mean that your engine should be neglected for its first 100,000 miles. Before that mileage interval is reached, the car will need several oil and oil filter changes, probably at least one PCV valve, and frequent under hood inspections.
Among the items your owner's manual may advise checking is the spark plug wires. Coccari suggests that if they aren't up to par, they may keep adequate electrical power from reaching the plugs and could result in fouling despite the advances of double platinum spark plugs. The hostile environment under the hood can lead to spark plug wire deterioration over time. In most cases, Coccari advises that the original wires will need to be replaced in four years or 50,000 miles.
Fully - Engineered Performance
Establishing, and following an extensive maintenance schedule is the key to adding life and value to any vehicle. Reading your owner's manual will give you the foundation for setting up a schedule for checking and changing your oil, filters and spark plugs, as well as inspecting other vital parts of the engine.
Allied Signal Automotive Aftermarket. is a leader in the North American replacement parts and original equipment service markets. Based in Rumford, RI, the unit markets and distributes Fram filters, Bendix brakes and Autolite electronics.
Courtesy of The Car Care Council
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