Common Misconceptions About W30 Engine Oil

The W30 oil lines, such as Amsoil 5W30 and Repsol Moto Matic 10W30, have been introduced to the Vietnamese market for quite some time. However, consumer understanding of this oil type remains quite vague. Therefore, the question of whether to use W30 oil has become a topic of debate recently, especially since many believe that thicker oil is better. Understanding this issue, Huynh Chau will share specific knowledge about W30 oil to help you make a more accurate choice.

Further reading:

• AMSOIL partners with Huynh Chau to strengthen market penetration in Vietnam
• Comparing two oil types: Amsoil Metric 10W40 and 10W30

Many people still misunderstand the W30 rating of oils.

1. Understanding the term "W30"

Before diving into the detailed information regarding the W30 specification, let’s explore the SAE viscosity ratings and their meanings.

The concept of SAE

SAE (Society of Automotive Engineers) is a technical standard established by the automotive engineering society in the United States. The SAE viscosity rating is used to determine the thickness or thinness of oil. Currently, most oil products on the market are multi-grade with SAE ratings such as 5W30, 5W40, 10W40, or 20W50,…

Meaning of the SAE viscosity rating

Taking Amsoil OE 5W30 as an example, the viscosity rating signifies the following:

• The number 5 before the letter W (which stands for Winter) indicates the lowest temperature at which the oil remains in a liquid state (not frozen) and can still be pumped for engine start-up. The calculation formula is: (the number before the “W” character) - 30. With an SAE of 5W, the vehicle can start at the lowest temperature of -25 degrees Celsius.
• The numbers following the W indicate how well the oil performs in positive temperature ranges. For SAE W30 oil, the optimal operating temperature is below 30 degrees Celsius. Conversely, the lower the viscosity rating after the W, the thinner the oil will be, and vice versa. For example, Amsoil 5W30 is thinner than 5W40 oil.

Further reading: What do the specifications on the oil bottle mean?

The SAE viscosity rating indicates the thickness or thinness of the oil.

2. Why do manufacturers recommend using W30 oil?

In a hot climate country like Vietnam, W30 oil is relatively thin and offers less protection to the engine compared to oils with ratings