Motor oil with a higher viscosity number is thicker.
Understanding Motor Oil Viscosity
The viscosity of motor oil refers to its thickness and resistance to flow. A higher viscosity means the oil is thicker, while a lower viscosity means it is thinner. Motor oil ratings, such as 5W-30, indicate how the oil behaves at different temperatures.
Here's a breakdown, as explained in our reference:
- Viscosity Rating: The rating is composed of numbers separated by 'W'. The first number (e.g., 5 in 5W-30) refers to the oil's viscosity at colder temperatures. The number after the 'W' (e.g., 30 in 5W-30) represents the oil's viscosity at 212℉ (100℃), an engine's average operating temperature.
- The Higher, the Thicker: According to the reference, a higher number indicates a thicker oil. For example, a 10W-40 oil is thicker than a 5W-30 oil at 212℉.
Viscosity and Engine Performance
Choosing the correct viscosity of motor oil is essential for engine performance.
- Too Thick: Oil that is too thick may cause increased friction and reduced fuel economy.
- Too Thin: Oil that is too thin may not provide adequate lubrication or protect the engine.
Practical Example
Let's look at examples of common motor oil ratings to determine which is thicker:
| Oil Rating | Viscosity at 212°F |
|---|---|
| 5W-20 | 20 |
| 5W-30 | 30 |
| 10W-30 | 30 |
| 10W-40 | 40 |
| 20W-50 | 50 |
Based on the table, we can see that 20W-50 is the thickest motor oil compared to all others listed, and 5W-20 is the thinnest. The higher the second number, the thicker the oil at operating temperatures.
Conclusion
In summary, a higher viscosity rating number means the motor oil is thicker. Always consult your vehicle's owner's manual to determine the appropriate viscosity of motor oil for your vehicle.
