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Types of Motor Oil

Suketu Mehta
Not everybody knows about the various types of motor oil available in the market. Learn about different motor oils and also the basis of their differentiation.
The basic job of engine oil is to prevent all metal surfaces in the car engine from laboring together and thus tearing apart due to friction. The oil should also be potent enough to resist all by-products of combustion.
All chemicals and acids collected in the engine are cleared by the engine oil, and it also ensures all parts of the engine are covered in oil. It also reduces oxidation at high temperatures. All these tasks are performed under extremely high temperatures and pressure levels.
The difference in all the types of motor oils is based on the way it is obtained, or on the conditions it is best suited for, as explained here.

Basic Types of Motor Oil

Conventional Motor Oil

This is the least expensive of all types. Conventional motor oil is mainly a byproduct produced during the crude oil refinement process. Since this oil does not have a complicated make-up process, it is liable for faster deterioration, when subjected to extreme heat. Conventional motor oil emits higher amounts of sulfur and other pollutants as well.

Synthetic Motor Oil

Synthetic motor oil costs more as it is expensive to produce. It is developed from polyalphaolefins, a chemical compound. It is developed from polyalphaolefins, a chemical compound.
The total structure of synthetic oils is unique and hence it is considered to be cleaner and stable than conventional oil. Also, this oil can maintain its flow under almost all conditions regardless of the heat and pressure.

Synthetic Blends

This oil combines properties of both synthetic as well as conventional motor oils. The idea behind synthetic blend oil is to combine the price of conventional oil with benefits of synthetic oil. Synthetic blend oils are a more refined version of conventional oils, which burn better and also stay stable at high temperatures.

High-mileage oils

As the name suggests, the oil is applicable for high-mileage engines that have spanned a distance of over 75,000 miles. High-mileage oils are known to reduce leakage from such engines, thus enabling their smooth functioning.

Different Motor Oils According to Gradation

Motor oils have been graded according to their viscosity properties by the Society of Automotive Engineers. The numerical code contains numbers followed by the letter W, like 0W, 15W and 25W.
Viscosity is gauged by measuring the time taken by the oil to travel through a standard opening at normal temperatures. The more time the oil takes to travel, the higher is its viscosity, and consequently a higher grade. Depending on the grade, the various types of motor oil are explained here.

Single Grade

There are 11 grades of this type―0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, 60. 'W' in these grades refers to 'winter'. Of these 11 grades, 6 of them are winter graded or a cold viscosity grade, indicating that these oils are to be used at lower temperatures. The ones without a 'W' can be used at higher temperatures, as they are hot viscosity grades.
Single grade motor oil is useful in places where the temperature remains mostly constant throughout and there are not many variations between hot and cold temperatures.


The oil in most vehicles is subject to wide temperature ranges. This makes it essential to have a motor oil which does not have a fixed viscosity according to the temperature and can adjust to changes.
For this purpose, certain special polymer additives are added to single grade oils to create multi-grade oil. This is the reason multi-grade oils have two viscosity grades, one each for cold and hot temperatures. For example, an oil coded as 20W-40 passes standards for both, 20W and 40 conditions.

Motor Oil Recommendations

All vehicle manufacturers state the kind of motor oil to be used in vehicles according to what they feel is most suited for the engines. However, a few recommendations for motor oils according to the viscosity and climatic conditions are given as follows:
  • 5W-30: This oil is used in most new cars and is very useful for starting the car in cold conditions.
  • 10W-30: This is the best engine oil for constant driving, and lasts better over longer periods of time.
  • 10W: Works best for driving in cold weather conditions
Since synthetic oil is very expensive, not many people use them. However, for anyone who wants high performance and best protection for the engine, this is the best option among all the types of motor oil available.