The concept of the internal combustion engine is the same as it was in the beginning, however, the concept of how to make an engine more powerful and fuel efficient is constantly changing and improving. Today’s engines are highly complex and require a skilled technician to repair and maintain them. Replacement engines cost on average $3000 to $5000 just for the unit, don't trust unskilled people to maintain it. We see engine failures due to using the wrong oil and many other maintenance mistakes and neglect.