Updated at: 26-07-2022 - By: Lucas

What role does motor oil play?

Oil lubrication is used in combustion engines. There are many roles that an engine oil serves in this system, including lubrication to reduce friction between moving parts and cooling of the pistons.

Engine part cleaning and chemical corrosion protection from combustion leftovers (e.g. cylinders, segments, pistons)

What is the role of car engine oil?

What Is The Main Function Of Motor Oil

Composition of the oils used in the heat engine lubricating circuits is very complex Different types of engine oil have different properties. 75-85% basic oils, 15% additions.

The primary purpose of the lubrication system’s fundamental oils is to provide lubrication. The basic oils, on the other hand, are determined by the raw materials utilized and the manufacturing process. fundamental oils are extracted in a variety of ways using oil as a starting point. Chemical techniques are used to produce synthetic base oils (synthesis). The most expensive option, but the best one. A mixture of 20-30 percent mineral oil and synthetic oil is called a semi-synthetic base oil (or synthetic blend).

Adhesives are organic substances (metal or polymer-based) that enhance the lubricating properties of the oils used in heat engine lubrication systems when combined with the base oil.

The chemical characteristics of the motor oil

Depending on the type of base oil, the production process employed, and the type and nature of additives used in the base oil, engine oils can have a wide range of qualities.

  • The lubrication and flow characteristics of the oils are unctuous and viscous.
  • Greasiness refers to the ability of oil to adhere to metal surfaces and form an oil-resistant film on them, preventing direct contact between moving parts. This eliminates dry friction, ensures maximum lubrication, and prevents wear and grip. Mineral oils are greasy enough to allow an internal combustion engine to run. To increase the oiliness of the base oil, additives are added.
  • Viscosity is the ability of oil to resist flow. The viscosity of the oil has a significant impact on the lubrication capacity of the moving parts, depending on temperature and speed, as well as the friction coefficient and power loss due to friction.
  • The oiliness and viscosity of the oil both have a significant impact on engine wear during startup. Because of the unctuousness, the moving parts are covered with an oil film, and the viscosity ensures that the oil can reach the moving parts quickly.
  • The temperature has a major influence on the viscosity of the oil, the higher the temperature, the less the oil becomes viscous and flows more easily. At low temperatures, however, the oil might freeze, resulting in a loss of flow capacity.

Engine oil circuit in a car

The oil’s freezing point is the point at which it stops flowing and begins to solidify. The freezing point of a 10W30 oil, for example, is 30 degrees Celsius.

The decrease in oil viscosity leads to:

  • reducing losses due to friction
  • reducing fuel consumption
  • the engine starts easier
  • a good engine operation at very low temperatures

The increase in viscosity leads to:

  • A decrease in oil consumption
  • Better sealing between the piston, the segments, and the cylinder
  • Kinematic viscosity of oil as a function of temperature

The viscosity of the engine oil should change somewhat as the temperature rises. It’s also important that the oil lubrication system can handle the varying viscosities of the oil and different engine testing.

Engine oil degrades due to a variety of factors. Another feature of motor oil is its oxidation stability. This refers to the oil’s capacity to retain its properties throughout time, whether it’s being used or stored.

Oil oxidation is hampered by high temperatures. Oxidation is more pronounced at higher temperatures and in the presence of oxygen.

At high temperatures and for lengthy periods of time, engine use accelerates the oxidation of the oil.

The degradation of oil is also caused by the presence of other compounds in it. Fuel, water, or coolant particles or contaminants can contaminate engine oil. Reduced viscosity is caused by fuel contamination (gasoline or diesel), which results in inadequate lubrication of moving parts. Oil’s self-ignition risk increases as its flammable temperature drops.

Oil emulsification and decreased lubrication capacity are the results of water or coolant contamination. It is also possible to separate the lubricants from oil due to an increase in viscosity. This reduces the oil’s lubricating capability significantly.

Incomplete combustion of the fuel causes particle pollution, which raises the oil’s viscosity. Metal particles (from parts) or airborne pollutants can also contaminate the oil. When oil particles come into touch with metal surfaces, the wear process is accelerated.

The additives of engine oil

Complex compounds, either organic or metallic in origin, that can be dispersed into and improve the properties of the lubricant are known as additives. The additives come in a variety of forms, each of which affects a specific aspect of the oil. The table below summarizes the principal additives in terms of their name and mechanism of action.

  • Aliphatic Compounds – Improve the oiliness of motor oil
  • Polymers – Improves cold fluidity and a hot viscosity
  • Detergents-dispersants – Works on oil-insoluble materials preventing the formation of deposits and neutralizing acid residues
  • Antioxidants, anti-corrosion, and anti-wear – Reduce the oxidation process of the oil
  • Rustproof – Helps to form an oil film on metal surfaces
  • Anti-foam – Reduces the process of foaming the oil (dissolving the air in the oil mass)

Engine oil classification

What Is The Main Function Of Motor Oil-2

The classification of engine oils is based on a variety of civil or military criteria. SAE, ACEA, API, and ILSAC are among the most regularly utilized standards in the automobile industry.

1. The SAE standard

Several international classification systems are used to classify heat engine oils. Following viscosity, SAE standards dictate the most prevalent type of classification.

Automobile oils are classified by SAE based on their viscosity at various temperatures. This is how oils are categorized:

  • monograde
  • multigrade

All the oils are categorized into 11 classes/degrees, starting at 35 oC and going up to the maximum operating temperature of the thermal engine.

The monograde oils

  • winter: 0W, 5W, 10W, 15W, 20W, 25W
  • summer: 20, 30, 40, 50, 60

At both the minimum and maximum temperatures, winter oils need to meet the standards for both their maximum viscosity and their minimum viscosity. Summer oils require only the bare minimum of viscosity at the hottest temperature.

Multigrade oils are utilized in Europe because of the fluctuation in summer and winter temperatures. They can be utilized in a range of temperatures between 0°F and 140°F.

2. The ACEA standard

The European Automobile Manufacturers’ Association (ACEA) divides motor oils into different categories based on where they will be used.

Including automobiles that run on either gasoline or diesel.

After December 22, 2014, the ACEA standard established in 2010 can be used to certify motor oils. On or after this date, ACEA certification will be required for all new motor oils.

There are three types of engine oils, each with a distinct purpose:

  • Ax / Bx
  • Cx
  • Ex

Engine oils are classified into 3 categories:

Standard quality, regular oil change interval, and low viscosity oil at high temperatures A1 / B1 (used to reduce fuel consumption)

It’s A3/B3/A3. Extends the interval between oil changes to a standard quality. Suitable for engines that are subjected to a lot of stress.

A3/B4 Direct injection diesel engines are recommended.

The A5 / B5 ratio. Preferably used in performance-oriented vehicles

C1 Standard quality, normal oil change interval, low viscosity oil at high temperatures, and low sulfur content make C1 a good choice (used for particulate filter engines or three way catalyst)

At high temperatures, C2 Standard quality oil has a very low viscosity (used for particulate filter engines or three way catalyst)

Normal oil change intervals and C3 standard quality are included in this package (used for particulate filter engines or three way catalyst)

C4 Standard quality, normal oil exchange range, and low sulfur content make it an excellent choice (used for particulate filter engines or three way catalyst)

For engines with exhaust after treatment systems (Cx), oils are categorized according to their minimum viscosity at high temperatures and sulfur content.

High temperature oil that has a low viscosity at high temperatures isn’t a good fit for all engines. Consult your car’s owner’s manual for the best oil option!

3. API standard

Depending on the engine, the American Institute of Petroleum (API) categorizes lubricants.

Diesel or gasoline are two options.

Spark-ignition petrol engines are under the purview of Category S. For category S, the grades in effect are as follows:

SM Stable long-term features for engines built after 2004 (oils with good oxidation stability, limitation of solid deposits, improved wear protection, and good performance at low temperatures)

SM oils are the best for gasoline engines according to the API standard, which specifies that SM oils are the most effective.

Diesel engines for automobiles and commercial vehicles are included in Category C. Category C grades include H4, I4, and J4.

H4 Since 1998, for vehicles requiring emission regulations to operate.

Engines with pollution standards in effect in 2004 can use I4 (with exhaust gas recirculation systems)

J4 Low sulfur content is recommended for particle filter engines built to meet 2007 emission limits.

For diesel engines, API-recommended J4 oils deliver the best results.

The advantages of synthetic oils

The components of synthetic motor oils are tightly regulated through chemical procedures. The best lubrication and engine protection are provided by synthetic motor oil and a full complement of additives. Synthetic oils have the following advantages over mineral oils:

  • lower viscosity at lower temperatures. The engine starts better.
  • better performance at high temperatures
  • solid deposits are harder to form