Which Oil is Thicker: 30-Weight or 40-Weight Motor Oil?

Discover why 40-weight oil is thicker than 30-weight oil and which is better for your engine's needs under different conditions.

Published

Video transcript

Oil viscosity is measured by its thickness; a 40-weight oil is thicker than a 30-weight oil at both operating and lower temperatures. This means 40-weight oil provides more lubrication under high-heat conditions, making it suitable for heavy-duty engines, whereas 30-weight oil is better for regular use.

Questions and answers

  1. What does 30-weight and 40-weight mean in motor oil?

    The numbers 30 and 40 refer to the oil's viscosity grade, indicating how thick or thin the oil is at certain temperatures—40-weight oil is thicker than 30-weight.

  2. Is 40-weight oil better than 30-weight oil?

    40-weight oil provides thicker lubrication, making it better for heavy-duty or high-heat engine conditions, while 30-weight is more suitable for regular everyday use.

  3. Can I use 40-weight oil instead of 30-weight oil in my car?

    It depends on your vehicle’s manufacturer recommendations. Using oil that's too thick can affect engine performance, so always check your owner's manual.