One of the reasons why the engines (inner burning) can some hight amount of oil is because the oil in the toplit of the cylinder leaking between valve pivot and valve bearing and going into the burning room. This leakag not only increases the possiblity of the burn oil and be left without oil but also causes air pollution and conceit amass in burning room valve top besides hest and upper surface of the piston and oil pollution. To prevent this situation decreasing the engines profit is brouided only using the valve stem seals in best quality