Spark plugs Memes

The fundamental difference between a functioning and non-functioning engine, displayed in spark plug form. That pristine top plug with its perfect electrode gap? It's creating the electrical arc needed for combustion. The bottom one looks like it's been excavated from a prehistoric tar pit. Mechanics see this and immediately know someone's been ignoring their check engine light for approximately 30,000 miles. Nothing says "I'll just drive it till it dies" quite like carbon deposits thick enough to qualify as geological formations.