What is the difference between 10W-30 and 10W-40?
Credit: Getty Images North America Getty Images News Getty Images
Q:

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

A:

Quick Answer

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.

  Know More

Full Answer

The viscosity of an engine oil is measured at two different temperatures: zero degrees Fahrenheit and 212 F. The first viscosity reading at zero is represented by the number in front of the W, meaning that both 10W-30 and 10W-40 oil have the same viscosity when cold. The number after the W indicates the viscosity at 212 F, with the number being higher the more viscous the oil is at high temperatures.

While both 10W-30 and 10W-40 are perfectly suited for use in warm environments, many experts recommend switching to a 5W-30 during the winter. This is because it will be slightly thinner at cold temperatures, which allows it to flow more easily through the engine. If the oil is too thick, it can make it difficult for the engine to start and run. This is turn can cause lowered fuel economy and can possibly damage the engine over time.

Learn more about Engine Oil

Related Questions

  • Q:

    How effective is synthetic blend motor oil compared to regular oil?

    A:

    Synthetic blend motor oil is more effective than regular oil because it lasts longer and can withstand higher temperatures without breaking down. Synthetic motor oils can improve vehicle horsepower and efficiency because they produce less resistance in an engine than regular motor oils.

    Full Answer >
    Filed Under:
  • Q:

    How is gearbox oil different from regular engine oil?

    A:

    The main difference between gearbox oil and regular engine oil is that gearbox oil facilitates the smooth functioning of gears instead of lubricating different parts of a car’s engine as regular oil does. Additionally, gearbox oil prevents gearbox noise when shifting gears, while engine oil helps clean the engine.

    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:

Explore