Oil weight what does it mean

Which means the 5W will be easier to pump. The best motor oil grade, The Drive reports, is the one your manufacturer recommends for your vehicle. But does it matter if instead of 10W, you add 5W? And what about ones for motorcycles? Modern motorcycle oils have many of the same additives as car oils, Motorcyclist reports. However, because motorcycle engines spin faster and share oil with the transmission, they require different oil additives.

And for extremely cold climates, some OEMs recommend going to a lighter-viscosity oil, Amsoil reports. Valvoline does not recommend doing this. Using a heavier grade than recommended may cause decrease in fuel economy, higher engine loads and eventually shortened engine life. Using a lighter grade than recommended may result in excessive mechanical wear and reduced engine life. For maximum engine performance, follow the recommended motor oil viscosity and maintenance schedule provided in your vehicle's owner's manual.

The "w" in motor oil stands for winter. The first number in the oil classification refers to a cold weather viscosity. The lower this number is, the less viscous your oil will be at low temperatures.

For example, a 5W- motor oil will flow better at lower temperatures than a 15W- motor oil. The higher the number, the thicker the oil at a specified temperature. In some circumstances, thicker oil can be used to compensate for increased bearing clearances gaps between bearing and rotating shaft that have developed over the years.

A large change in bearing clearances can result in poorer lubrication. For best performance always follow the recommendations for motor oil viscosity in your vehicle's owner's manual.

In general, oil's viscosity actually decreases as it heats up. Manufacturers typically uses additives to achieve temperature-specific viscosity ratings, and those ratings are certified with multiple tests. Cold testing usually ranges from degrees Celsius to degrees Celsius 14 degrees Fahrenheit to degrees Fahrenheit , according to Fenske.

Testers want to see if the oil will be thin enough for the engine to turn over, and to flow once the engine is running. At low temperatures, oil can thicken to the point that it actually solidifies. Hot testing is done at temperatures between degrees Celsius and degrees Celsius degrees Fahrenheit and degrees Fahrenheit , Fenske said. In these tests, the focus is on seal leakage and the ability of the oil to protect internal engine components when it's in a thinner state. You may have noticed the numbers on oil bottles getting lower recently, with some oils even wearing a 0W rating.

That's largely down to efficiency, according to Fenske. Thinner oils produce less friction, meaning less energy is required for rotating engine parts to move. Modern engines are designed to run with these thinner oils, so excess wear shouldn't an issue, Fenske noted. Watch the full video for more details on how motor oil works. A lot of engineering goes into the numbers on each bottle of oil.

Sign up to get the latest performance and luxury automotive news, delivered to your inbox daily! I agree to receive emails from Motor Authority.