What Do Oil Viscosity Numbers Mean? Oil viscosity refers to how thick or thin the oil is and how well it flows at different temperatures. This is represented by the numbers you see on oil bottles, such as …

Castrol's oil viscosity chart makes it easy to understand oil weight, thickness and grades. Understand how viscosity affects your engine's performance.

Dec 17, 2025 · This guide will demystify oil viscosity grades, explaining what those numbers signify and empowering you to make the best oil choice for your vehicle, ensuring optimal engine protection and …

Sep 25, 2025 · It refers to measuring an oil’s resistance to flow or thickness. They are typically represented by numbers and letters, such as 5W-30 or 10W-40. The first indicates the oil’s viscosity …

Viscosity, simply put, is the measure of a fluid’s resistance to flow. For engine oils, viscosity dictates how easily oil flows at specific temperatures. Higher-viscosity oil is thicker and flows more slowly, …

Read on to discover everything you need to know about SAE oil ratings and the meaning of oil numbers, plus see our handy oil viscosity chart to get a better understanding of exactly how it works.

What do motor oil numbers mean? The numbers on oil labels are viscosity grades. They identify the thickness of the oil and its ability to flow at certain temperatures. This is commonly referred to as oil …

Nov 5, 2025 · In this article, we explain oil viscosity in simple terms—how it affects your engine and why those numbers on your oil bottle matter. Motor oil is essential for engine performance and longevity, …

Jan 4, 2026 · Understand the crucial viscosity code that dictates how engine oil flows and protects your motor from wear in both cold starts and high heat.

In simple language, the first part of the viscosity designation (W grade) is an indication of the product's ability to help an engine crank and start and for the engine to pump the lubricant. The lower the …