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.
Pure heptane has two main uses. The first use is as the standard zero point for the octane rating scale for gasoline. As a driver, you may have noticed that higher octane fuel is more expensive because it is better for your engine. You can correctly conclude that a fuel rated zero octane would be terrible for your car.