Has there been more smoke than usual coming out of your exhaust system? Excess exhaust emissions can appear concerning, but there can be a fix behind it. The combustion chamber in your engine is designed to burn a mixture of air and fuel – that’s it. As your mileage increases, oil can contaminate the combustion chamber. This condition, known as oil blow-by, often results when friction and metal-to-metal contact have worn parts and created gaps between the cylinder walls, piston rings and valve guide seals.