The difference between 5W-30 and 5W-40 synthetic oil is primarily in their viscosity, or thickness.

5W-30 oil is a thinner oil that is designed to flow more easily at lower temperatures, making it a good choice for use in cold weather. It also has a lower viscosity at higher temperatures, which can improve fuel efficiency and reduce engine wear.

5W-40, on the other hand, is a thicker oil that is designed to provide better protection for the engine in high-performance and high-stress situations. It provides better lubrication at higher temperatures and under heavy loads.

Both 5W-30 and 5W-40 synthetic oils are designed to provide better protection for the engine than conventional oils. They are made from a combination of synthetic base oils and advanced additives, which provide better protection against wear, corrosion, and deposits.

Can you mix 5w30 with 5w40 oil?

It is generally not recommended to mix different viscosity oils, such as 5W-30 and 5W-40, as it can potentially cause damage to the engine. Mixing different viscosity oils can cause the oil to lose its intended properties and performance.

When two different oils are mixed, the resulting oil will have properties that are somewhere in between the two original oils. For example, if you mix 5W-30 and 5W-40 oil, the resulting oil will have a viscosity that is somewhere in between the two, which may not be suitable for your engine. Additionally, the oil may not perform as well in cold weather or high temperatures, which could lead to increased wear and tear on the engine.

It is generally recommended to use the oil viscosity recommended by the manufacturer in the vehicle owner manual. In case of oil change, it’s always best to use the same oil viscosity that was in the engine before. If you are unsure which oil to use, consult with a certified mechanic or the vehicle manufacturer.