Gasoline engine oil

Regardless of the class of car, the issue of selecting oil is of interest to all buyers. Work is recommended to be trusted by car service employees. They will pick the right one.

Characteristics of oil for a gasoline engine


Compared to mineral and semi-synthetic, synthetic ones win. But not everyone can afford them due to the cost. The structure is initially homogeneous when the distillation is just over. Mixtures and additives are added to it to fit the current standards.

Mineral fluids contain impurities of sulfur, among other substances. The engine will last a long time if the indicator is at the level of 1 percent. The service life is halved if you purchase a fake with a parameter above 1%. Such compounds are cheaper, they are changed every 15 thousand kilometers.

In the manufacture, they rely on complex chains of synthesis of chemical reactions in order to achieve the required performance.

Synthetic endowed with the following advantages compared to other types:

  • replacement is required every 20-25 thousand kilometers. The period varies depending on the operating conditions. To a smaller or larger side;
  • long service life;
  • the composition is not subjected to waxing and oxidation;
  • synthetic oil remains neutral to overheating – at critical temperatures it does not lose its positive qualities;
  • gasoline consumption is reduced, and engine power is increased;
  • viscosity is reduced, due to which the liquid penetrates into every corner of the engine.

Semi-synthetic – the average between mineral and synthetic compounds. Filling with additives, quality and cost balance each other.

SAE Gasoline Engine Oil Viscosity Grade

  • winter is marked with the letter W, next to which there are numbers from 0 to 25;
  • SAE 20-60 – summer group;
  • all-weather – combine the properties of two types.

The operational properties are evaluated according to the American and European standards: the ability to resist wear, detergent properties, protection against oxidative and corrosion processes.


S and C are two categories into which compounds are divided according to the conclusions of the American Petroleum Research Institute. The categories are for diesel and gasoline. For cars up to 2000, markings with the letters SG, SH, SJ are used. After the two thousandth, SL and SM are added.

European manufacturers have developed a universal ACEA certification system. According to this scheme, the letter E is applied to the fluid marking for trucks according to this scheme, the letter B for diesel. The letter A denotes gasoline engines.

Strict adherence to the instructions from the manufacturers is required when choosing the appropriate viscosity grade. But it is permissible to be guided by other recommendations if the manufacturer does not give clear recommendations.

The values ​​of average winter temperatures in the region are the basis for calculations when choosing a winter fluid.

  • 25W. At -5 degrees;
  • 20W – For 10 degrees below zero;
  • 15W. Up to 15;
  • 10W – up to -20;
  • 5W – up to – 25;
  • 0W – -30 and below.

It takes some time to move through the lubrication system. You will have to wait, starting the engine, until the liquid reaches all the rubbing parts. A mode called “oil starvation” is activated. An increase in wear and friction is noted.

The better fluidity is maintained at negative temperatures, the faster everything moves. Such engines are not afraid of negative effects.

Manufacturers recommend choosing a SAE 40 or higher class for those who are interested in liquids for use in the summer. There is a direct relationship with the voltage inside the internal combustion engines.

In various zones, the following parameters are taken into account:

  1. shear speed.
  2. Pressure specific type.
  3. Temperatures above zero.

Viscosity retention is significant even under such severe conditions, otherwise it is not enough to cool the pairs involved in friction to form a film coating. The task is important when it comes to preventing premature wear.

The technical data section contains the pour point parameter. It is calculated based on the results of laboratory tests.

Oil performance decreases earlier when temperatures are lower. Then even a regular lubrication system will not help pump the liquid.

Buyers are advised to focus not on the temperature at which the compositions solidify, but on the SAE, viscosity class. The first is used only for advertising purposes.

The dimensionless quantity is the viscosity index. It shows how wide the temperature range of the oil is. When the viscosity index is large, the indicator is less dependent on changes in the temperature plan.

Quality class

Quality class

From the point of view of the API, compositions with the designation SJ \ SF are recognized as universal. They are poured into all gasoline and diesel engines.

In the ACEA classification, the design characteristics of engines from Europe were most fully taken into account. The same applies to operating conditions in European regions.

For individual tests, the ACEA requirements are more stringent than those of the API. It is recommended to give preference to fluids that have passed ACEA tests.

For gasoline engines use the designations A1, A2, A3. Diesel engines use the letters B1, B2, B3, B4 and so on.

A1 and B1 are high quality low viscosity fluids. They are used to achieve maximum fuel efficiency. They are used where manufacturers set the appropriate requirements.

A3-96 and B3-96 are classes whose characteristics are perfect.

Composition differences

The main difference lies in the molecular base, its structure. In the production process, molecules with a given set of characteristics are combined with each other. Synthetic ones reach a maximum in chemical and thermal stability, unlike mineral ones.

Chemical stability means that no performance degradation occurs.

Without thermal stability, the viscosity and fluidity of the oil is not able to maintain its index over a wide temperature range. Thanks to this, the engine starts easily and simply in the cold. And in the highest temperature zones there is additional protection.


Problems with the transition

Problems arise if the owner of the car used poor quality oils before. Or violated the intervals for its replacement. Because of this, the sealing elements lose their elasticity – partially or completely.

Under the influence of mineral water, deposits inside the engine are gradually “washed out”. They go layer by layer. Due to synthetic oils, deposits flake off the inner surface. For this reason, the oil receiver mesh can become clogged, as well as oil channels.

“Oil starvation” is activated. The result is a quick breakdown. Gland seals take up deposits. Eliminate barriers preventing leaks.

It is not recommended to use synthetic fluids:

  1. For rotary piston engines.
  2. When there is a running-in with the relevant requirements or after a major overhaul. Only high quality mineral oil is used for break-in.
  3. With stuffing boxes. Leaks are possible here.
  4. In the presence of sealing elements that have lost elasticity.
  5. With internal surfaces that have deposits.

Types of oil for a gasoline engine

Chemical composition

Mineral options are made directly from petroleum. It all starts with distillation, then the oil fractions are purified using selective or acid purification. For synthetics, the organic synthesis method is preferred. The basis is from the same oil products, but the processing of the feedstock is deeper.

There are several types of synthetic oils created from:

  1. Complex ethers.
  2. Silicones or polyorganosiloxanes.
  3. glycols.
  4. polyalphaolefins.

These substances are mixed in different proportions.

Semi-synthetic group. They are formed by adding substances obtained in the synthesis of organic matter to mineral oils. Engine oil without additives is called base oil.

Polyalphaoleins. Synthesis reaction from ethylene – this is how these substances are obtained. Ethylene belongs to the group of the simplest alkenes. Homogeneous molecular composition is one of the main, but not the only feature.

Fluids based on PAO-synthetics have a number of advantages:

  1. Extended service interval.
  2. The engine starts confidently at low temperatures.
  3. Detergents – keep the engine clean.
  4. Preservation of chemical properties throughout the entire operational period.
  5. Resistance to oxidative processes.
  6. Carbon monoxide consumption is low.
  7. Friction is reduced, increasing economy.
  8. With high antifriction properties.

How to choose oil for a gasoline engine

Selection and recommendations of the manufacturer

  • Compatibility of engine materials with the acquired composition;
  • degree of wear. When calculating it, they are guided by mileage;
  • operating conditions can be heavy or light, medium;
  • the type of motor and the year it was built.

In some models, old nitrile rubber seals and gaskets are installed – they are incompatible with modern synthetic fluids. Synthetics are allowed to be used only when the parts are replaced with other, high-quality ones.

If you follow the manufacturer’s recommendations, the engine will last a long time and correctly. It is allowed to use oils with a slightly different class. It is only important to remember about the different operating temperature ranges.

It is undesirable to use an oil more viscous than recommended by the manufacturers. The oil pump pumps such liquids worse. Increased wear is one of the consequences in situations where a more fluid material is taken.

Operation and degree of wear

Operation and degree of wear

It is necessary to make adjustments not only for recommendations, but also for the climate in the region. It is not recommended to mix compounds with different properties – their compatibility has not been proven. Seasonal liquid is rare on the market, it is used most often as a temporary option until a better one is selected.

The motor requires different oil in different periods of operation. Special varieties are used during break-in. It is not recommended to change it for a certain period.

After the run-in is completed, the quality of the composition can be increased. Viscosity, improved temperature stability contributes to the extension of the resource. After some time, the performance decreases again.

As the motor wears out, fluid consumption increases, as does the likelihood of leaks. At one gas station, the mileage is 10 thousand kilometers. With aggressive driving and using a diesel engine, replacement is carried out more often.

As necessary, the driver monitors the level of the composition and tops it up. It is not recommended to abruptly switch from one brand to another. The proportion of topped-up, new oil should not exceed 15 percent.

Synthetic does not mix with mineral. The incompatibility of additives leads to a deterioration in properties, an unpredictable change. Synthetic fluid is mixed with others if the manufacturer is the same.

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