Engine Maintenance

How Often Should You Change Spark Plugs


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Determining how often to change a spark plug on a vehicle involves several factors. Checking the owner's manual will reveal the recommended plug change interval. Driving conditions and overall mechanical shape will impact recommended spark plug service, too.

Spark Plugs Have Improved

Spark plug and vehicle technologies have come a long way. Some cars in the 1950s had a recommended interval of 5,000 miles for changing the plugs. Today, through advancements in design and materials, some cars can meet or exceed 100,000 miles without a change. A 4-cylinder 2009 Hyundai Accent has its first recommended spark plug change at 30,000 miles for both normal and severe conditions. Likewise, a 4-cylinder 1990 Honda Accord recommends a plug change every 30,000 miles or two years.  

"Long-Life" Plugs

Several manufacturers advertise "long life" spark plugs. Using precious metals such as silver, platinum, gold and iridium, these plugs have an advertised life close to 100,000 miles. An 8-cylinder 2010 Hyundai Genesis has a recommended plug change interval of 97,500 miles, driving in normal conditions, using iridium-coated plugs.

Poor Plug Symptoms

If you detect performance problems like slow pickup or poor gas mileage, check your spark plugs as a possible cause. Replace them if you find evidence of damage to the insulator (body near the head) and the electrode (metal points that form the "gap").

Fix Vehicle Problems to Extend Plug Life

Various mechanical conditions contribute to quicker spark plug wear. The piston rings may wear out, letting oil seep in and foul plugs. The distributor and ignition wires may wear out, resulting in less electrical power delivered to the plugs. DodgeRam.info displays a list of spark plug damages and their likely causes. Correct the deficiencies and you can likely increase your plug life to the miles recommended in the owner's manual.

With continuous development of new technology for vehicles and plugs, spark plug lives will keep increasing. Removing and checking the plugs yourself can give you valuable clues on when they need replacement. Changing the plugs when needed is a cheap investment for keeping your car running strong.

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