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.
Top fuel drag racing is a class of automotive racing where cars run on 90% nitromethane and 10% methanol. Top fuel drag cars are long and narrow, have large rear tires and extremely narrow front tires, and very little sits between the driver and the explosive powertrain.