Functions of Oil

1. OIL SEALS.
     Oil creates the seal between the moving piston rings and the cylinder walls, and between the valve stems and the valve guides. This sealing action keeps the oil out of the combustion chamber & the products of combustion out of the oil. The better the seal, the more power is transmitted to your crankshaft, & the greater the engine's efficiency.

2. OIL COOLS.
    Temperatures in the combustion chamber range between 2,000°F and 3,000°F. Water in the engine block carries away much of this heat, but if it were not for the oil which cools the cylinder walls & the pistons, your engine would run red hot, & ultimately not function at all. In addition to cooling the cylinders & pistons, it carries heat away from bearings, valves, and other moving parts of the engine.

3. OIL CLEANS.
     One of oil’s most basic functions is to keep your engine clean. Carbon deposits are constantly being formed on cylinder walls (this build-up can be much more rapid in improperly tuned or poorly functioning engines). The piston rings, which move on a thin film of oil, tend to remove these deposits in a squeegee-like action just as a wiper blade removes the accumulated road grime from your windshield when it rains. These carbon deposits that are removed fall right back into the oil pan.
     When you wash clothes, you don't use dirty water . . . likewise, you shouldn't use dirty oil to clean the carbon from cylinder walls. Clean oil will remove dirt better than dirty oil . . . its plain common sense!

4. OIL LUBRICATES
     Maintaining proper lubrication is important for the efficient operation of an internal combustion engine. Oil as a lubricant decreases the power required to overcome friction and reduces wear between rubbing and bearing surfaces. Proper lubrication results in increased power and longer engine life. In theory, if oil were kept 100% clean, and if adequate oil pressure were maintained at all times, there would always be a thin film of oil between bearings and journals; and with no contaminants present, there would be nothing to cause wear.
     Of all the physical and chemical properties that oil may have, it is generally agreed that the characteristic called viscosity is the most important. All other things being equal, it is the viscosity that determines the friction loss, heat generation, mechanical efficiency, load carrying capacity, film thickness, lubricant flow, and, in many cases, wear. The viscosity of oil is a measure of its fluid resistance to flow and is regarded as its internal or fluid friction. The degree of contamination can be an important determinant of viscosity and can adversely affect the lubricating properties of oil.