“If vehicles were humans, engine oil would be the blood.”

This phrase alone is enough to figure out the importance of engine oil in a car. If you happen to own a car, you might already know how crucial it is to change the engine oil from time to time. But there’s a lot to know about it than just changing it as and when your mechanic says. This article covers everything you need to know about engine oils.

What is Engine oil?

It is basically a lubricant used to overcome friction between the moving parts of the engine thereby increasing the power output and service life. It consists of base oils enhanced with additives which include anti-wear additives, depressants, viscosity index improvers and corrosion and oxygen inhibitors. These additives are mixed with base oils which include petroleum-based hydrocarbons or polyalphaolefins (PAO) or their mixture.

Why Engine oil and effects on performance

The engine is one heck of a machine. It is the working house for various other moving parts. The moving of these many parts cause a lot of friction between them, and also the temperature could rise to a significant degree. To reduce the friction between the parts, and to keep engine from overheating, engine oils are used.

Engine oil creates a separating film between surfaces of adjacent moving parts to minimize direct contact between them, decreasing heat caused by friction and reducing wear, thus protecting the engine.

The purposes of using engine oil are many, however, some main purposes are:

  • Lubricating
  • Cooling
  • Cleansing
  • Sealing

Cleaning and Sealing are the less effective effects, but they can’t be completely neglected.

Selecting the best oil for your car?

There are a variety of engine oils available in the market and it can be pretty difficult to choose the best suited for your car without proper knowledge of it. Selecting the right engine oil for your car is a crucial part of extracting the best performance out of it. Although the best way to know the right engine oil for your car is to see the manufacturer’s manual, it is really important to understand the instructions properly.

To know the best oil for your car, first, you need to know the types of oils.

Broadly, two types of oils are available, conventional and synthetic. Further classifications are also made on the basis of nature of oils.

  • Conventional Oil

Conventional oil is the byproduct of the decomposition of plants and animals that lived long ago. But these conventional oils are mixed with various additives to make a new range of oils called the Premium Conventional Oils. It is the most common among consumer car makers. It is available in all common viscosities. Car manufacturers usually specify 5W-20 or 5W-30 oil, though some require 10W-30. These three ratings cover just about every light-duty vehicle on the road

  • Synthetic Oil

Synthetic oil is born in a laboratory and is made for high tech engines. They are superior and high performance in all aspects, from viscosity index to protection against engine deposits. They flow better at low temperatures and maintain peak lubrication at high temperatures. But they are  expensive than conventional oils and are not generally not used by many in  common vehicles.


Reading Labels of Synthetic Oil Containers.

Manufacturers often suggest oils according to their grades or viscosity ratings which are given by the Society of Automotive Engineers (SAE). These standards and symbols are always printed on the label of the oil container, you just need to know how to read and understand the what do these codes and symbols mean.

Viscosity Ratings:

Two types of oils are available in the market on the basis of viscosity

  • Single Viscosity Oil
  • Multi-Viscosity Oil

Almost every vehicle is designed to run on multi-viscosity oils.

In the broadest possible terms, the viscosity is the resistance to the flow of liquids. In the engine oil ‘world’ viscosity is notated with the common “XW-XX” designation. The number preceding the “W” rates the oil’s flow at 0 degrees Fahrenheit (-17.8 degrees Celsius). The lower the number here, the less it is affected by cold weather i.e., the less it thickens. For example, 5W-XX will thicken more than 10W-XX. “W” stands for winter. So a car being driven in cold climates needs less thickening oil and thus the oil is selected accordingly.

The number after the “W” indicates the oil’s viscosity measured at 212 degrees Fahrenheit (100 degrees Celsius). This number represents the oil’s resistance to thinning at high temperatures. For example, 10W-30 oil will thin out at higher temperatures faster than 10W-40 will.

To find out which viscosity to choose, look for the oil viscosity chart in the manufacturer’s manual.

Oil Classification Codes:

The standards for oil are set by the International Lubricant Standardization and Approval Committee (ILSAC), a collaborative effort of U.S. and Japanese automobile manufacturers. A generalized symbol is established to identify the two types of oils on the basis of usage in type of vehicles

  • For Gasoline Vehicles
  • For Diesel Vehicles

The starburst symbol on an oil container label means that the oil meets the current engine protection standard and fuel economy requirements of ILSAC.

(a) API starburst symbol, (b) API donut symbol for gasoline engine oil, and (c) API donut symbol for diesel engine oil.

Useful Tips

  • Use only the oils suggested by your manufacturer. It is always best to follow the manufacturer’s guidelines unless you have a good reason and know everything about it.
  • Check the oil regularly. One of the most common mistakes made by people is not replacing the oil at the right time. You must replace the oils regularly. Recommended cycle is every 5000 miles or 6 months, whichever comes earlier.

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  1. Very helpful tips you have shared. Glad that I came across such an article. That’s an amazing article. Gained a lot of knowledge about how oil change works. Thanks for sharing this article.Engine oil acts as a lubricant and lubricates different moving parts of the engine. But with the flow of time it becomes degrades and degraded oil can’t do it’s function properly. Therefore ,its really important to find the right choose.Thanks for sharing such great tips and informative article.


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