Q:

What is the difference between 5w-20 and 5w-30?

A:

The difference between 5w-20 and 5w-30 oil is that 5w-30 oil has a higher viscosity at its operating temperature. Viscosity is the term used to describe the thickness of a substance, in this case oil, where a higher number indicates a thicker oil.

Oil viscosity varies inversely with temperature. This means that as the temperature goes up, the thickness (viscosity) of the oil decreases. To use this knowledge in an automotive application, it is important for an oil to be thin enough to spread quickly when a cold engine is started, yet it should not become too thin once the engine reaches its operating temperature. An oil with the rating of 5w-30 is a multiweight oil that will act like a 5-weight oil, which is very thin at cold temperatures, while maintaining the thickness of a 30-weight oil once the engine reaches its operating temperature. This protects the engine from wear at both temperature extremes.

The invention of the modern multiweight oil is made possible by the addition of polymers, which coil up at cold temperatures and mimic shorter molecular chains with a lower viscosity. As the oil's temperature rises, these polymer chains begin to unwind, increasing the effective length of the molecular chain and thereby increasing the viscosity.


Is this answer helpful?

Similar Questions

  • Q:

    What is the difference between 10W-30 and 10W-40?

    A:

    The main difference between 10W-30 and 10W-40 motor oil is that 10W-40 has a higher viscosity, which means that it will remain thicker at higher temperatures than 10W-30. Viscosity means a liquid's resistance to flow, and normally a higher viscosity is a good thing for oil, as it acts as a better lubricant and creates a stronger seal.

    Full Answer >
    Filed Under:
  • Q:

    What is the difference between 10w30 and 5w30 oil?

    A:

    The difference between 10w-30 and 5w-30 oil is the thickness of the oil during cold weather conditions, 5w-30 being the thinner of the two and therefore recommended for colder operational climates. Engine oil is rated on a viscosity scale by the Society of Automotive Engineers, which determines its cold- and warm-weather rating; the cold rating is indicated by a “w” for winter.

    Full Answer >
    Filed Under:
  • Q:

    What is the difference between 10w30 and 10w40 oil?

    A:

    The two oil types differ in their high temperature viscosity, and 10w40 is thicker than 10w30 when it comes to high temperatures. Before multi-grade oils were formulated, car owners typically used 10w30 for its wintertime flow properties, while relying on the 10w40 for the summertime when temperatures warmed up.

    Full Answer >
    Filed Under:
  • Q:

    How was oil made?

    A:

    According to the American Petroleum Institute, oil or petroleum is a naturally occurring liquid derived from ancient fossilized organic matter. This fossil fuel is found in geological formations beneath the Earth's surface.

    Full Answer >
    Filed Under:

Explore