An internal combustion engine is subject to wear and tear. Regular maintenance, such as timely oil changes, and responsible driving habits—such as warming up the engine gently and periodically applying sufficient load to achieve high temperatures, thereby preventing internal pollution—contribute to a longer lifespan. As parts become dirty or worn, noises may arise, engine performance may decline, or oil consumption may increase. There may also be issues of cause and effect. For example, unburned oil entering the exhaust can cause damage to the catalytic converter.
When wear is suspected, a diagnosis can be made based on measurements. This can be done both with external measuring equipment on the engine, such as a compression test using an oscilloscope (cylinder pressure measurement), as well as by examining and measuring disassembled parts with tools like the caliper and cylinder wear gauge.