What is the viscosity of motor oil? Is it important?

Viscosity is considered one of the most important criteria for selecting the right engine oil for vehicles. However, even though Vietnam holds the title for having the highest number of motorcycles in Southeast Asia, many customers still lack knowledge and proper awareness about this concept.

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Viscosity is usually clearly indicated on the label of the oil bottle.

1. What is the viscosity of oil?

The SAE viscosity grade or SAE standard (Society of Automotive Engineers) is a classification system established by an association of engineers in the automotive motorcycle industry to categorize the viscosity levels of various oils.

In other words, the viscosity of engine oil is a parameter that indicates the ease of pouring oil at a specified temperature. Viscosity can also be simply understood as the thickness or thinness of the oil.

Viscosity is the standard for classifying engine oil.

2. The role of viscosity

By reading the viscosity specification—this index is usually publicly displayed on the label—we can accurately determine the thickness or thinness of the oil. This enables us to choose the right oil type that matches the vehicle, conditions, and usage requirements, maximizing the lubricating properties of the oil and the performance of the vehicle's engine.

>> See more: Answers to frequently asked questions when choosing motorcycle oil.

Viscosity indicates the thickness of the oil, allowing for product selection.

3. Classification of engine oil by viscosity

Based on the SAE viscosity standard, engine oil can be divided into two types: single-grade oil and multi-grade oil. Single-grade oil is typically designated as SAE + "number," for example: SAE 30, 40, 50…

On the other hand, multi-grade oil is indicated with a more complex label - xWy, where "W" stands for winter. The number before the W (x) represents the starting temperature in winter, and the number after the W (y) indicates the viscosity at 100 degrees Celsius (when the vehicle is operating). The higher the Y number, the thicker the oil. For example: 5W40, 10W30, 10W40, 20W50.

>> See more: How to properly check motorcycle oil like an expert.

Multi-grade engine oil is widely used and popular.

Single-grade oil has a lower operational temperature range compared to multi-grade oil. Specifically, single-grade oil maintains its viscosity at high temperatures but can become thick and difficult to circulate at lower temperatures. This can lead to slow