Modern cars require about as much maintance as a toaster except for the fluids and filters about the only thing that needs attention are the spark plugs. Many manufactures recommend replacement as high as 100K. The advent of many new electrode metals, platinum the most popular, have allowed this as the recent engineering of fluids extended there life. I think that many hours of testing go into the spark plug selection so I only recommend replacing with the recommended. There are several gimmicks on the market and none of them work so stay away from them. The only one I have used is the Champion truck plug and I didn’t notice any improvement but they looked great with the gold body.There are 2 common types of plugs the tapered and gasket. Except for access on some vehicles replacement is simple. I do recommend using a torque wrench mandatory when installing the ones with a gasket and will prevent future problems with the tapered. The crush of the gasket is crucial to provide a proper seal and never reuse the gasket. The tapered will be easier to remove if not over tightened and none are easy to remove at 100K. One last tip when replacing plugs consider replacing the wires and put a dab of dielectric grease on the connector it will prevent corrosion and make the wire easier to remove.