Engine Oil


You would be in luck if you woke up this morning wondering, “I wonder how much I know about car engine oils.” We present an overview of the basics of car engine oil.

What’s car engine oil?

Engine oil is an essential component of your engine’s longevity and performance. The lubricant keeps all the metal parts from breaking apart or joining together to form the coolest boat anchor in the world. Your engine could be destroyed in seconds without car engine oil.

What’s the origin of car engine oil?

Two components make up car engine oil: base oils and additives. These two components work together to create your final product in your engine. Consider coffee as an analogy: the base oil is water, and the additive package is the coffee beans.

The largest proportion of car engine oil is made up of base oils. They are used to lubricate the internal moving parts of the car, absorb heat, and seal the piston rings.

Base oils for car engine oils can contain either petroleum or chemically synthesized substances.

Crude oil is refined into conventional or petroleum base oils. Crude oil contains contaminants such as sulfur, nitrogen, and oxygen. These elements cannot be removed completely by the refining process. Oil refining separates different types of molecules by their weight. This results in molecules that are similar in weight but differ in structure. This reduces the oil’s performance.

Synthetic base oils are engineered to contain only beneficial molecules. Synthetic base oils are free from contaminants and molecules that aren’t necessary for their intended purpose. Because of their versatility, they have uniform molecular structures that are more efficient than conventional lubricants. They also provide superior friction-reduction, fuel efficiency, film strength, and extreme temperature performance.

Additives to car engine oil

A car engine oil’s additives include chemicals that provide anti-wear and anti-foam, corrosion protection as well as acid neutralization, viscosity preservation, detergency, dispersancy, and anti-foam properties. Some examples of chemical additives are boron, phosphorus, zinc, and phosphorous. It is difficult for oil formulators to find the right balance between the engine additives and the base oil. This is especially true as vehicles become more sophisticated and demanding.

What does a car’s engine oil need to do?

Modern car oil is a highly specialized product that engineers and chemists have carefully designed to perform many important functions. A car engine oil must…

Reduce Friction

Lubricants minimize friction between components and reduce wear.


Lubricants keep internal cleanliness in check by suspending contaminants or preventing contaminants from adhering to components. Base oils have a range of solvency levels that aid in maintaining internal cleanliness. Solvency refers to the fluid’s ability to dissolve solids, liquids, or gases.

Regents keep crucial components like pistons clean and working properly.

Although oil’s solvency is crucial, detergents as well as dispersants are also important. Engine additives such as detergents prevent contaminants from adhering to parts, particularly hot ones like piston rings or piston pistons. Dispersants are additives to engine fluids that prevent contaminants from adhering to components. Dispersants are engine additives that act as solvents, keeping the oil clean and preventing sludge from forming.


Reduced friction reduces heat transfer to moving parts. This lowers equipment’s operating temperature. Lubricants can also absorb heat from contact surfaces and transport it to a place to be safely dispersed, like the oil sump.

Fun Fact: The amount of oil needed to lubricate an engine is very low compared to the amount required to cool these internal parts.


In places like the piston ring/cylinder interfacing, car engine oil acts as an effective dynamic seal. The dynamic seal keeps combustion gases within the combustion chamber. This maximizes horsepower and prevents hot gases from contaminating car engine oil in its sump.

Dampen Shock

The impact of mechanical shock can be cushioned by a lubricant. High-functioning lubricants can resist rupture and absorb energy spikes across a wide contact area. The mechanical shock to components can be dampened, which reduces wear and other damaging forces, increasing the component’s operating life.

Protect Against Corrosion

Internal component corrosion must be prevented or minimized by a lubricant. This can be achieved by either chemically neutralizing corrosive materials or by creating a barrier between components and the corrosive.

Fun Fact: Car oil does not have the natural ability to resist corrosion and rust; these properties must be obtained through the use of engine additives.

Transfer Energy

Car engine oil is extremely compressible and makes a great energy-transfer medium. It can be used to lift hydraulic valves or to replace components in engines with variable timing.

The most important property of car engine oils is their viscosity. The oil will flow faster if it has a lower viscosity than water. Oils with a lower viscosity flow slower, just like honey.

What’s viscosity?

The most important property of oil is viscosity. It refers to the oil’s resistance against the flow. Variations in temperature affect the oil’s viscosity. It is thinner at high temperatures and thicker at low.

Car engine oil must flow at low temperatures to lubricate and protect the engine during startup. However, it must be thick enough to protect the engine in high temperatures. As with most engines, oil viscosity should not change when used at different temperatures.

It would be useful to have a number that indicates the oil’s viscosity. It’s called Viscosity Indice (VI). It measures the viscosity (or viscosity) of oil at 40°C (104°F) and 100°C (212°F). The lower the VI, the more the oil will protect the engine from temperature changes. Full synthetic oils have a lower VI than traditional oils.

These SAE viscosity ratings indicate the ranges within which oil falls. It is suitable for cold temperatures. Think of the “W” symbol as “Winter.” The numerical classifications increase in number, and the lower the number, the more oil can be used to provide engine protection. Higher numbers indicate better protection in high-heat or high-load conditions.

Multi-viscosity oils make up the majority of today’s oil. This means that they react differently at different operating temperatures. It provides the best of both worlds: good cold flow when it drops and reliable protection once it reaches operating temperature. A 5W-30 oil for cars performs at 40oC like a SAE5W oil and at 100oC like a SAE30 oil.

How do you classify petrol engine oil?

American Petroleum Institute (API) developed a classification system to help identify oils that are formulated to meet different operating requirements for petrol and diesel engines. There are two main categories in the API system: C-series or S-series.

The S-series service class emphasizes the oil properties that are essential to petrol engines. After passing a series of engine and bench tests (API Sequence), oil can be sold with the appropriate API service classification. As the lubricant performance improves, the classifications are alphabetized. Each classification is replaced by the previous one. Oils that meet the API SN-PLUS latest classification may be used in any engine that calls for them or any previous API specification, except where otherwise stated.

The API SNPLUS category replaces all previous ones. The SN-PLUS oils were designed to…

  • Increased resistance to oxidation
  • Deposit protection
  • Maximum fuel economy
  • Performance of the emission-system
  • Resistance to a new engine knock, low-speed pre-ignition (LSPI),

How is diesel engine oil classified?

The C-series classifications are for diesel engines. They include the ones shown below. All C-series classifications are not equal. The new FA-4 classification is only applicable to certain 2017 and newer diesel engines. The FA-4 classification was created to maximize fuel economy for over-the-road trucks.

What is the main takeaway?

This is a lot of information. But it boils down to this: car oil is much more than a commodity. It is essential for the engine’s longevity, performance, and safety. Although the initial cost of high-quality, fully synthesized oil is higher, it can last for a lifetime and be much cheaper than conventional oil. This is especially true if you have extended drain intervals.

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