The sexist definition in the dictionary describes a sexist as a person who shares sexist beliefs and participates in sexist behaviors. Sexist beliefs are beliefs that revolve around sexism. The word sexist can describe the nature of a comment or gesture, as well.
So how long do they typically last? Well, standard copper plugs are said to last anywhere from 10,000 to 20,000 miles (16,093 to 32,187 kilometers), while more expensive iridium or platinum spark plugs can last 60,000 miles (96,561 kilometers) or more [source: Spark plugs UK].
How often should I replace my spark plugs? A: Unfortunately, there is no single answer to this question. As spark plugs grow older, they lose their sharp edges as material from the center and ground electrodes is slowly eroded away. As the gap between these two points grows, the voltage required to bridge the gap increases proportionately. Even the best ignition systems will be strained to supply enough voltage to completely burn the fuel. It is at this point, when fuel is being left unburned, that the time has come to change spark plugs. Replacing worn out spark plugs with new ones (with sharp new edges) effectively restores the ignition system's efficiency.