Why Motor Engine Oil Comes in Grades
Have you ever wondered which oil is favorable for your automobile at various temperatures?
The simple answer is that some specific oils are better suited for varying temperatures.
By the end of this post, you will be able to understand better why motor engine oil always comes in various grades, what the grades are, and what each grade of motor engine oil does in the engine.
The different oil grades and different oils are better suited for varying temperatures.
What Is Motor Engine Oil?
Motor Engine oil is a substance that is made up of base oil, anti-wear additive, dispersant, detergents and for multi-grade oils, viscosity index improver.
What Are Motor Engine Oils Used For?
They are employed for the lubrication of moving parts.
It neutralizes acids that emanate from fuel and from the oxidation of lubricants.
It also cools the engine by transmitting heat away from running parts.
How Is Motor Engine Oil Graded?
Motor oil is graded based on its viscosity qualities by the society of automotive engineers (SAE).
Society uses numerical code in evaluating motor oils, for example, SAE40 are slim when heated.
Oil producers were required to begin with thick oils, but it was problematic to kick-start the engine in cold conditions since it would not crank.
Oil additives were introduced that permitted oil thin out less quickly(i.e. retain a high viscosity index).
Different Motor Engine Oil Grades
You might see different grades, for example, You see SAE 15W-30, or SAE5W-40.
Now there are two different values here.
Let us understand what they mean.
So there is one set that tells us the oil performance in cold temperatures(0W, 5W, 10W, 15W, 20W, 25W, 30W, 40W, 50W, and 60W).
The second value measures for a much higher temperature(8,12,16,20,30,40,50).
The higher the viscosity the higher the SAE code. Larger numbers are thicker.
The SAE has separate viscosity for gear and manual transmission oils.
How Does Each Grade of Motor Engine Oil Work at Different Temperatures?
The value with the W represents how the oil functions in lower temperatures while the second value after the W measures much higher.
For example, SAE15W-30.
The oil acts as a SAE15 at cold temperatures(15W for winter) and like a SAE30 at 100 degrees.
Note: The W stands for winter.
The lubricant with a low viscosity grade the easier it is for the engine to start cold.
They have more fluidity and more liquid will flow more easily but thicker ones will not flow under such conditions.
Higher grades are suited for higher temperatures, which will flow well and help form a protective film across engine parts.
In low temperatures it is better to choose an oil with a low viscosity grade to facilitate oil movement in your car during cold engine start, they are less thick and therefore more fluid and require less work done by the oil during startup.
So a 5W is better suited to a lower temperature than a 15W.
Classical Types of Motor Engine Oil Grades
Monograde Motor Engine Oils:
These are oils that function over low temperature range.
They have single grading for example either you see SAE15W or the SAE30. They are used in older vehicles.
During winter you use the one with the W and during higher temperatures you use the one without the letter W
Multigrade Motor Engine oils:
They are used in modern cars They are multi-graded for example SAE15W-30. They are more temperature resistant.
Conclusion
I hope that at the end of this article we can now be able to understand and identify the different grades of engine oil.
Victor is a graduate of Industrial Engineering with vast hobby in sharing knowledge to others.
As a Science, Technology, and other related field enthusiast , he loves to write and share information relating to engineering and technology fields, science and environmental issues, and Technical posts.
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