Wear is the progressive damage, involving material loss, which occurs on the surface of a component as a result of its motion relative to the adjacent working parts. Most contacting components in an engine are provided with a supply of lubricant to avoid excessive wear and subsequent damage, which may occur if they were allowed to contact in dry conditions. The consequences of wear in an engine can be severe and can lead to complete engine failure in some cases. Other effects can be loss of performance, an increase in oil consumption, a decrease in fuel economy, and an increase in emissions.