Oil weight refers to the viscosity of an engine oil, or how easily it flows at different temperatures. Viscosity is a measure of a fluid’s resistance to flow, and is affected by factors such as temperature and pressure.
When it comes to engine oil, the weight rating is often expressed as two numbers separated by a “w”, such as 5w-30 or 10w-40. The first number, the “w,” stands for “winter,” and refers to the oil’s cold temperature performance. The lower the number, the better the oil performs in cold temperatures. The second number refers to the oil’s high-temperature performance, and the higher the number, the more resistant the oil is to thinning out and losing its protective properties at high temperatures.
In general, lower viscosity oils (i.e. those with a lower first number) flow more easily at lower temperatures, providing better cold-start protection and allowing oil to reach critical engine parts more quickly. However, these oils may not provide as much protection at high temperatures, and may break down or thin out more quickly.
Conversely, higher viscosity oils (i.e. those with a higher second number) offer better protection at high temperatures and under heavy loads, but may not flow as easily at low temperatures. Using an oil with too high of a viscosity rating for a particular engine can cause excessive wear and reduced fuel economy, while using an oil with too low of a viscosity rating can result in increased engine wear and decreased protection.
It’s important to consult your vehicle owner’s manual or a trusted mechanic to determine the recommended oil weight for your particular vehicle and driving conditions. Additionally, it’s important to use high-quality oils that meet industry standards and are formulated for the needs of your engine. Regular oil changes at recommended intervals are also crucial for maintaining the health and longevity of your engine.