Most motor oils are made from a heavier, thicker petroleum hydrocarbon base stock derived from crude oil, with additives to improve certain properties. The bulk of a typical motor oil consists of hydrocarbons with between 18 and 34 carbon atoms per molecule.7 One of the most important properties of motor oil in maintaining a lubricating film between moving parts is its viscosity. The viscosity of a liquid can be thought of as its "thickness" or a measure of its resistance to flow. The viscosity must be high enough to maintain a lubricating film, but low enough that the oil can flow around the engine parts under all conditions. The viscosity index is a measure of how much the oil's viscosity changes as temperature changes. A higher viscosity index indicates the viscosity changes less with temperature than a lower viscosity index.
Motor oil must be able to flow adequately at the lowest temperature it is expected to experience in order to minimize metal to metal contact between moving parts upon starting up the engine. The pour point defined first this property of motor oil, as defined by ASTM D97 as "... an index of the lowest temperature of its utility ..." for a given application,8 but the "cold cranking simulator" (CCS, see ASTM D5293-08) and "Mini-Rotary Viscometer" (MRV, see ASTM D3829-02(2007), ASTM D4684-08) are today the properties required in motor oil specs and define the SAE classifications.
Oil is largely composed of hydrocarbons which can burn if ignited. Still another important property of motor oil is its flash point, the lowest temperature at which the oil gives off vapors which can ignite. It is dangerous for the oil in a motor to ignite and burn, so a high flash point is desirable. At a petroleum refinery, fractional distillation separates a motor oil fraction from other crude oil fractions, removing the more volatile components, and therefore increasing the oil's flash point (reducing its tendency to burn).
Another manipulated property of motor oil is its Total base number (TBN), which is a measurement of the reserve alkalinity of an oil, meaning its ability to neutralize acids. The resulting quantity is determined as mg KOH/ (gram of lubricant). Analogously, Total acid number (TAN) is the measure of a lubricant's acidity. Other tests include zinc, phosphorus, or sulfur content, and testing for excessive foaming.
The NOACK volatility (ASTM D-5800) Test determines the physical evaporation loss of lubricants in high temperature service. A maximum of 14% evaporation loss is allowable to meet API SL and ILSAC GF-3 specifications. Some automotive OEM oil specifications require lower than 10%.
What attracts customers to the garage?
Car repair shop can be a good source of income for the true expert of repair cars. Of course, the most difficult are the origins and often need a few years to make your mark and gain the trust of customers. The best way is of course to provide services at the highest level. Diligent work, inform the owner repaired the car of any new defects that come to light during the breakdown, and of course the price adequate to the service is a guarantee that the customer will come back to us as well - that recommend us to their friends. It should also take care of the order in the workshop, which will certainly builds a good impression and encourages undecided people to use our services.
Used car parts - worth it?
In many cases, the maintenance of vehicles made by a real expert in the field of electronics or auto mechanics is essential. Many people, however, will perform the repair at his own expense, using commonly available knowledge in this area. In this case, the preferred embodiment may be used to purchase a car parts. Admittedly, car parts, which have already been used can be a bit tired, but they tend to be several times cheaper than new equipment. No wonder that the automotive aftermarket is booming, and the exchange between the owners of auto parts may be getting more efficient, for example, thanks to the Internet.