Wikipedia about oil
An oil is any neutral, nonpolar chemical substance that is a viscous liquid at ambient temperatures and is both hydrophobic (immiscible with water, literally "water fearing") and lipophilic (miscible with other oils, literally "fat loving"). Oils have a high carbon and hydrogen content and are usually flammable and slippery.
The general definition of oil includes classes of chemical compounds that may be otherwise unrelated in structure, properties, and uses. Oils may be animal, vegetable, or petrochemical in origin, and may be volatile or non-volatile. They are used for food, fuel, lubrication, and the manufacture of paints, plastics, and other materials. Specially prepared oils are used in some religious ceremonies as purifying agents
Why is it better to take the car to a mechanic, than to repair it personally?
Often our cars are accidents and then it is necessary to repair. Many of us are doing it on their own, however, such a solution for many reasons may not be a bad idea. Why is it like that? When we repair all by yourself, we can never be sure that we can deal with failure. We can not be confident that the repair will be successful, and if you're stuck at a standstill, the situation may cause us many problems. Good workshops give us confidence that the car will be repaired, and often a guarantee that will work for a long time, and when it breaks down, however, parts will be replaced at the expense of the mechanical plant. It is much safer solution.
How to recognize a good mechanic?
Each car from time to time need of repair - minor defects is quite a normal thing. It happens also that the car must travel a serious review. Whatever the situation, you might want to have a trusted mechanic who well knows his job. But how to find it? A good solution is to ask your friends if they could recommend someone suitable. Reputation in such a case often provides the highest quality services. In addition, if a mechanic can quickly find the cause of problems with the car and is able to immediately determine the extent of repairs needed and valued service and the cost of parts - most likely we are dealing with a trustworthy expert.