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.
The most common fuels used in race cars these days (2007) are: 1. Leaded and unleaded gasoline. This fuel is used by many types of race cars and octane levels are usually high, meaning 94 and above. Gasoline is used in drag cars, rally cars, stock cars, and even Formula One cars. Gasoline is derived from the distillation of crude oil. 2. This fuel is used by Champ Cars and was formerly used by Indy Cars.