Regulation of iron absorption and transport. Iron for use in synthesis of heme, iron-sulfur centers and other non-heme iron proteins is obtained from the diet and via release of recycled iron from macrophages of the reticuloendothelial system that ingest old and damaged erythrocytes (red blood cells).
Four-stroke oil is more like the oil used in cars but both 2-stroke and 4-stroke oil serve the same purpose - to keep the engine lubricated. Four-stroke dirt bike oil comes in a variety of weights like 10w-40, 20w-50 and so on. It is not mixed with gas.
Best Answer: Use either Amsoil or Lucas brand synthetic oil 20 W 50 in the newer bikes 89 and up. Here is a little secret that Harley does not tell you. They do not make their oil, It is made by Sunoco gas company. They were the lowest bid in the war to put the Harley name on an oil. Source(s):