5W-30, 10W-30 or 10W-40: how to choose engine oil viscosity

What the numbers on an engine oil bottle mean, and how to choose between 5W-30, 10W-30 and 10W-40 for cars driven in Malaysia.

The viscosity grade printed on an engine oil bottle, such as 5W-30 or 10W-40, tells you how thick the oil is at two temperatures. Choosing the grade your engine was designed for is the single most important step in choosing an engine oil.

What the two numbers mean

The first number with the W (for winter) describes how the oil behaves when the engine is cold. A lower number means the oil flows faster at start-up, reaching moving parts sooner.

The second number describes how thick the oil stays at normal operating temperature, around 100 °C. A higher number means a thicker oil film when the engine is hot.

Choosing between the three EVShield grades

5W-30 fully synthetic suits modern engines, including turbocharged engines, built with tight tolerances. EVShield 5W-30 meets API SP and ILSAC GF-6.
10W-30 semi synthetic suits cars driven mostly in town, with frequent stop-and-go traffic. EVShield 10W-30 meets API SN/CJ-4.
10W-40 semi synthetic gives a thicker hot film and is widely used in Japanese, Korean and Malaysian cars. EVShield 10W-40 meets API SP.

Check the specification too

Viscosity is only half of the label. The API or ILSAC specification, such as API SP, shows the performance standard the oil meets. Use an oil that meets the specification listed in your owner’s manual or a newer one.

Not sure which grade fits your vehicles or fleet? Send us an enquiry with the make, model and year, and we will recommend a grade.

Serving Kuala Lumpur, Selangor and Johor

A4 Petroleum supplies EVShield 5W-30, 10W-30 and 10W-40 engine oil to workshops, fleets, car dealers and resellers in Kuala Lumpur (KL), Selangor, Johor and across Malaysia. WhatsApp +60 12-886 6025 for a price.

Frequently asked questions

What does the W in 5W-30 mean?

The W stands for winter. The number before it shows how easily the oil flows when cold; a lower number flows faster at start-up.

Is 10W-40 thicker than 5W-30?

Yes. At normal engine operating temperature, a 40 grade is thicker than a 30 grade, and a 10W grade is thicker than a 5W grade when cold.

Which grade should I use for my car?

Use the viscosity grade and specification shown in your vehicle owner's manual. If several grades are listed, choose based on the engine's age, design and how the car is driven.

Where can I buy EVShield engine oil in Kuala Lumpur, Selangor or Johor?

Order directly from A4 Petroleum in Cheras, Kuala Lumpur. We supply EVShield 5W-30, 10W-30 and 10W-40 to workshops, fleets, car dealers and resellers in KL, Selangor, Johor and across Malaysia, with carton and bulk orders available.