The thicker oil is determined by the number on the right side of the "W" in an oil's viscosity rating. For example, a 10W-40 oil is thicker than a 10W-30 oil at operating temperature.
Here's why:
- Viscosity measures how easily a fluid flows. Thicker oils have higher viscosity and flow more slowly.
- Multigrade oils have two viscosity ratings, one for cold temperatures (the number before the "W") and one for hot temperatures (the number after the "W").
- The higher the number, the thicker the oil at operating temperature.
Example:
- A 10W-40 oil is thicker than a 5W-30 oil because the 40 is greater than the 30.
In Summary: When comparing oils, look at the number after the "W" to determine which is thicker.
