Many people don't know how to select motor oil that will help them get optimum performance out of their car. People often just select the oil their father used, or they may take the suggestion of a counter person at an auto parts store that may not know any more about cars than they do.
There are meaningful differences in motor oils and choosing the right one can have a major impact on how well your car runs. Selecting the right oil is often the quickest and cheapest way to improve your car's performance and reliability. Two components determine how well motor oil will perform in your car. One factor is the base oil, and the other is the combination of chemicals (additives) that are added to the base oil.
Base oils
The two primary types of base oils used are mineral and synthetic. Mineral oils are by-products of refined crude oil. Refining helps reduces the impurities but leaves molecules of all shapes and sizes. Synthetic oils are manmade compounds whose molecules are all the same size and shape; consequently, synthetic oil has a less friction and performs significantly better than mineral oils.
What to choose
The easiest way to select motor oil is to follow the good, better best model:
GOOD - Mineral-based (regular) motor oils. These are the cheapest and most widely available oils. They typically use standard additive packages that provide minimum levels of performance and protection.
BETTER - Synthetic motor oils. These man-made oils are more expensive that mineral-based oils but are still widely available. Their performance advantages come predominantly from the synthetic base oil used. They have a longer service life and offer some improvements in protection.
BEST - High-performance synthetic motor oils. These motor oils are the most technologically advanced oils. Although they significantly outperform mineral based or synthetic motor oils, they are about the same price as standard synthetic motor oil. They are typically only available through auto parts stores and select oil change centers. These oils primarily differ in their uses of more advanced, proprietary additive technologies.
Additives
Regardless of the base oil used, chemicals must be added to give motor oil the characteristics needed to do its job. Typical additives that may be added to base oil include detergents to reduce the formation of residue, deferments, to deter absorption of air, anti-wear agents, antioxidants and others.
Although additives are typically only 15 to 25 percent of the make up of motor oil, they can impact a lubricant's performance much more than the base oil. For instance, mineral based motor oil with a very good additive package can easily outperform synthetic motor oil with a mediocre additive package.
There is no easy way for a consumer to determine the quality of a motor oil's additive package. Price is often an indicator of quality since the more advanced additive technologies cost more to produce. Performance is the ultimate measure of quality.
Then there is the issue of what viscosity oil to use. Viscosity is the measure of how thick an oil is. This is the most important property for an engine. It is a measure of the oil's resistance to flow. the more resistant or "thick" the oil, the higher its viscosity. An oil with too low a viscosity can shear and loose film strength at high temperatures. An oil with too high a viscosity may not pump to the proper parts at low temperatures and the film may tear at high rpm.
A system for rating the viscosity of oils was established many years ago by the SAE. An oil's viscosity rating is often referred to as its "grade" (or from times past, its 'weight'). An oil that flows more quickly has a lower viscosity and, consequently, is given a lower rating. Grade numbers are assigned to certain ranges of viscosity ratings. For example, an SAE 30 grade covers a lower range of viscosities than an SAE 40 grade.
Multigrade oils, such as a 10w30 oil, are formulated to flow rapidly to areas requiring lubrication when the engine is cold but also to maintain enough viscosity to protect the engine at higher temperatures and operating loads. The number before the 'W' (for Winter ) is the oil's viscosity when cold. The number after the 'W' is its viscosity at operating temperatures.
I recommend following the engine manufacturer's suggestions for viscosity grade when choosing an oil for normal driving conditions. Particularly, keep in mind that when driving in cold climates, an oil with good start-up and flow behavior is preferred, such as a 5w30 or 10w30. An older, more worn engine may be better protected with a higher viscosity oil, like a 10w40 or 20w50. Engines that operate in a warm climate may only require a higher viscosity, single grade engine oil, SAE 30 or 40 for example. Turbo-charged and high-performance engines may need an oil that lubricates well at start-up but also continues to protect with the engine is hot, perhaps a 15w40 or even 20w50 in warmer weather.
Viscosity Index or VI is a measure of how much an oil's viscosity changes with temperature changes. The higher the VI, the less change that occurs and the better the protection.
Then there is the oil rating system, i.e how is a certain companies oil rated according to the American Petroleum Institute. The groups that standardized the oil rating system are the Society of Automotive Engineers (SAE), the American Society for Testing and Materials (ASTM) and the American Petroleum Institute (API). These three entities collaborated to provide the rating system as it is today.
The current service ratings came about by testing done by the American Petroleum Institute (API). The service ratings classification system starts with SA and proceeds to SM as of 2005. According to the API’s motor oil guide SM, SL & SJ are the current rating levels that are being used for gasoline powered vehicles. Ratings below SJ are considered obsolete which means they are for older vehicles. API recommends motorists refer to their owner’s manual before deciding which service rating is correct for their vehicle. API has a different guide for diesel powered engines
Then there are the multigrade oils. these are oils which can be used for either a diesel engine or a petrol engine. They can be very well identified my reading the dual nature of the oil as in the API ratings for a diesel and a petrol engine.e.g SM/CF, however it recommended to use a genre based oil.
I hope this guide helps all those people who have problems in choosing the right oil for their car and would just stop going for brands and colours like SHELL yellow or blue. casue i personally think the shell oils here in pakistan arent really that good u can get a better oil in the same price.
All positive replies will be appreciated and so will be any mistakes which i had made
P.S , however it is also noted that some comapnies void your warranty if u use a synthetic oil, khair that is a very huge debate and jsut stubborn companies say that however that wont be ther problem here in pak. It is also advised not to use any mineral based oil more than 3500 to 4000km run here in pakistan if u want to keep it in optimum condition and dont want to get an overaul at 10000km as manufactureres recommend and a max of u can say 8 to 10 K for a synthetic oil changign the oil filter definitely at 5K not more
