Engine oil is one of the most important fluids in a vehicle and plays a crucial role in lubricating, cooling, and protecting internal components. Choosing the right engine oil directly impacts engine performance, durability, and efficiency . But with so many brands, viscosity grades, and quality standards available, how do you choose the right engine oil? In this article, we examine quality classifications and international standards for engine oil and provide important tips for selecting the right engine oil.
Chapter One: The Importance of Using High-Quality Engine Oil
Engine oil fulfills several important functions in a car engine:
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Lubricates moving parts : reduces friction and wear between parts.
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Cooling : Helps dissipate heat from hot engine parts.
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Cleaning : Absorbs impurities and prevents deposits.
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Corrosion protection : Forms a protective layer on the metal and thus prevents rust.
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Sealing : Helps improve compressibility in the cylinder.
Using poor quality or unsuitable engine oil can result in increased fuel consumption , reduced engine performance, overheating or even complete engine failure .
Chapter Two: Engine Oil Viscosity Grades (SAE)
One of the most important criteria for selecting an engine oil is viscosity , which is defined by the Society of Automotive Engineers (SAE) . This indicator characterizes the oil’s resistance to flow at different temperatures.
2-1. Seasonal oil
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For example: SAE 30, SAE 40
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Suitable for climates with constant temperatures.
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Nowadays it is hardly used anymore.
2-2. All-season oil
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For example: 5W-30, 10W-40
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The number before the letter W (Winter) indicates the fluidity of the oil in cold weather (the lower the number, the better the fluidity).
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The number after the W indicates the oil concentration at high temperature.
Table for selecting viscosity depending on the ambient temperature:
| Oil viscosity | Applicable temperature range |
|---|---|
| 0W-20, 5W-20 | very cold climate (cold regions) |
| 5W-30, 10W-30 | Temperate climate (most modern cars) |
| 10W-40, 15W-40 | warmer regions or older cars |
| 20W-50 | Extremely hot weather or engine wear |
Tip: Always check the manufacturer’s recommended viscosity in your vehicle’s owner’s manual.
Chapter 3: Engine oil quality standards (API, ACEA, ILSAC)
3-1. American Petroleum Institute (API) standards
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Petrol: SN, SP (new generation)
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Diesel engines: CK-4, FA-4
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The higher the second letter, the higher the quality of the oil (e.g. SP is better than SN ).
3-2. ACEA standards (European Union).
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Popular categories:
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A/B : Suitable for petrol and light diesel vehicles.
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A : Suitable for engines with catalytic converter (low ash content).
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E : Suitable for heavy diesel vehicles.
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3-3. ILSAC standards (Japan, USA)
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The most common brands: GF-5, GF-6
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Suitable for Japanese and some American cars.
Oil separator with funnel-shaped floating tank and Joule heat absorption function
Chapter 4: Engine oil types based on base oil and additives
4-1. Mineral oils
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The cheapest type
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Suitable for older cars.
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shorter life expectancy
4-2. Semi-synthetic oil
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A mixture of mineral and synthetic materials.
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Good value for money.
4-3. Fully synthetic engine oil
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Best quality and high temperature resistance.
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Suitable for new and turbocharged vehicles.
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More expensive, but worth it in the long run.
Chapter five: Signs of bad or inferior engine oil
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The color changes to black (a sign of heavy soiling )
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the smell of burning
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Oil level is low, no leaks (burnt oil)
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increased engine noise
Chapter Six: Golden Secrets to Choosing the Best Engine Oil
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Refer to your vehicle’s owner’s manual to ensure you are using the recommended viscosity and oil specification.
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Pay attention to the weather conditions : use thinner oils in winter and thicker oils in summer.
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Buy well-known brands like Mobil, Shell, Castrol, Total, Valvoline .
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Change your oil regularly : usually every 5,000–10,000 kilometers (depending on the oil type).
Finally
Choosing the right engine oil depends on the viscosity (SAE), the quality standard (API/ACEA), and the oil type (synthetic/mineral) . Following these recommendations will protect your engine from wear and improve its performance. Always check for signs of oil wear and change the oil when necessary.
If you have any questions about choosing engine oil, let us know in the comments section!