Posted by vishal Motor Oil, Tips and Articles

Motor Oils Q&A

The quality of lubrication an engine receives affects the life and performance of that engine. Even if you use the finest of service parts, poor lubrication or incorrect lubrication can seriously damage the engine.

What is the purpose of motor oil?

Motor oil in any engine does 5 key jobs:

  • Reduces friction between moving parts.
  • Reduces heat.
  • Cleans dirt and debris from the moving components.
  • Assists in compression by sealing by creating a film between valve guides and piston rings and cylinder walls.
  • Cushions engine parts from the force of combustion.

Motor oils consist of several additives which contribute to the formulation and performance of engine oils. Most petroleum based motor oils consist of refined crude oils and additives. Additives are blended in during the refining process to enhance the existing quality an oil has, add a property it lacks or one which was lost in the refining process.

Why is it important to maintain the correct type of oil?

The oil in an engine is constantly being churned by moving parts. During this process air and other gases may mix into the oil causing it to foam. In an engine foam does not allow proper lubrication causing wear between moving metal parts shortening the life of the engine. It is important to choose an oil with viscosity rating approved by the vehicle manufacture.
Viscosity is the tendency of a liquid to resist flowing. Some addatives in motor oils allow under a wider temperature range. Viscosity is of a fluid is designated by the viscosity number.

Currently there are 2 main types of oils available:

  • Mono grade oils: Oils tested at one one temperature
  • Multi grade oils:  Oils tested at more than one temperature.

Most automobiles in today’s market are manufactured to run on multigrade oils.
What do the different numbers on the oil containers mean?

There are many numbers on the oil bottles found at most fueling stations. Letters and numbers such as SAE 40, AP, 5W40, 10W30 are the type of letters and numbers commonly seen.

They refer to oil viscosity, based on a scale established by the Society of Automotive Engineers (which is where the “SAE” comes from). The scale rates oil from a low of 5 to a high of 50. As you’ve probably noticed, most automobile motor oils have two numbers. These are multi-grade oils. The first number describes viscosity at low temperatures. The second number refers to viscosity at normal engine operating temperatures. For example: the “5” in a 5W-30 motor oil will protect an engine down to an air temperature of about -25 degrees Fahrenheit. The “10” in a 10W-30 is good if the lowest temperature where you live is likely to be in the neighborhood of -10 or so. As for the “30,” that is well-suited for the typical temperatures that most cars operate at these days. If you are driving a racing car, or pulling a heavy trailer on a hot summer day, you might want the higher-temperature protection afforded by a motor oil with a second number of, say, 50. (As for the “W,” it indicates that the oil is designed to work well in cold weather).

What’s the difference between conventional oil and synthetic oil?

The differences between the two are many but some of the most common ones are:

  • Composition: conventional oils have a lower temperature rating and therefor a shorter life between drain time. Synthetic oils have a higher temperature rating allowing the oil to last longer before it deteriorates and looses its qualities.
  • Cost:  synthetic oils could cost as much as twice as much as conventional oils and this is a factor that deters many consumers. It’s commonly argued that even though synthetic oils cost more, they are better for the engine and the duration between oil changes is delayed.

Vehicle manufactures now specify the type of engine oil suited to be used in the vehicle. Almost all new cars now require the use of synthetic oils since most vehicles have high compression engines and are designed to produce lower emissions.

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