Engine oil viscosity grades explained
What is Engine Oil Viscosity Grade?
Engine oil viscosity grade measures a lubricant’s resistance to flow at specific temperatures. Established by the Society of Automotive Engineers (SAE), it indicates how easily oil flows to protect engine components during cold start-ups (low temperature) and under normal operating conditions (high temperature).
What Do the Numbers in Engine Oil Grades Mean? (e.g., 5W-30)
In a multigrade oil designation like 5W-30:
- The "5" (Winter Rating): Represents oil fluidity at low temperatures. Lower numbers mean easier cold starts and faster protection in freezing weather.
- The "W": Stands for "Winter" (not weight).
- The "30" (Operating Temperature Rating): Represents oil thickness at 100°C (212°F). Higher numbers mean a thicker protective film at high temperatures.
Engine Oil Viscosity Grades Comparison Chart
| Viscosity Grade | Cold Start Performance (Winter) | High Temp Protection | Ideal Application / Vehicle Type |
| 0W-20 | Excellent (down to -35°C) | Thin / High Fuel Economy | Modern engines, Hybrids, Extreme cold climates |
| 5W-30 | Great (down to -30°C) | Balanced Protection | Most modern passenger cars, SUVs, Light trucks |
| 5W-40 | Great (down to -30°C) | High / Heavy Duty | High-performance, Turbocharged, Diesel engines |
| 10W-40 | Good (down to -25°C) | Strong Film / Moderate | Older engines, High-mileage vehicles, Moderate climates |
| 15W-40 | Moderate (down to -20°C) | Maximum High-Temp Protection | Heavy-duty diesels, Commercial fleet vehicles |
How to check and change your engine oil
Follow these steps to successfully check the oil level of your car.
Understanding engine oil standards
Here is everything you need to know about the three standards used to describe engine oils.
What is engine oil composed of?
Let’s take a closer look at what goes into this essential lubricant, and the role of the main additives used.
