A low mileage engine refers to a used engine that has been driven significantly fewer miles than average, typically under 60,000 miles. Because it has experienced less wear, internal components like pistons, bearings, and valves remain in better condition. These engines are often sourced from accident-damaged vehicles, Japanese imports, or rarely driven private cars. They offer better compression, less oil consumption, and a longer remaining lifespan compared to high mileage alternatives. While a low mileage engine generally costs more upfront, it provides greater reliability and fewer repair needs, making it a smarter long-term investment for any engine replacement job.