How to choose oil

How to choose oil ?
Instructions on the oil market, the brand will often appear “SAE” and “API” “SAE” is used to assess the oil viscosity followed by a 5 to 50 the number of ranges, the larger the number the more viscous oil, whereas the more dilute. “API” series of assessing the merits of the oil with “S” for gasoline (the country with “Q” that gasoline) “C”, said diesel oil next level of English letters, “A” at the lowest level, “G” the most advanced , used a “C” “D” and “F” and other levels, such as “API CD” says “API” specification for diesel engines “D” grade oil.
    Appropriate choice of engine oil viscosity is very important to not “SAE” The higher the number the better, according to the local level to determine the temperature and the car. Generally speaking, in Guangdong and other southern regions, the average car engine oil can be used “SAE” 30 至 40 “API” CC and CD (diesel) or “API” SD and SE level (gasoline) and oil must be high-class cars Guide to information based on the manufacturers to choose, not random selection.
    In addition there is a wider use of multi-grade oil with a “W” said, adding the polymer material, in addition to the general characteristics of the oil, its viscosity can be adjusted within a certain range, thickens when exposed to heat, cold thinning, thus reducing the engine running and wear resistance.
    Usually by oil base oil and additives composed of two parts. They use a mineral oil base oil, additives, there are metal detergent, oxidation corrosion agents, rust removers, ashless dispersant and viscosity index improving agent. Add some oil chemicals with special features to improve the quality of oil, reduce engine wear not only extend the life of the machine, making the piston and combustion chamber cleaner, oil filter, just on the road and small deposits, but also save fuel, oil changes extend the use of mileage, oil change period is generally up to more than ten thousand kilometers or more.
    In general, high speed and load gasoline less, low oil pressure, engine speed low load, the oil pressure is high, both for oil performance requirements are different, so depending on the type of engine oil is also different in two ways, one species called the gasoline engine oil, and another called diesel oil, the two can not be mixed. As there is a market for both gasoline and diesel can be used for general-purpose oil, its performance meets the engine oil level two overlapping values, so also indicating the scope of application of the oil level, and not for all cars.