Mixing different grades of engine oil, such as 5W30 and 10W40, is generally not recommended. It is preferable to use the recommended grade of engine oil as specified by the manufacturer of your vehicle. However, in certain situations, if you find yourself in need of topping up your oil and only have different grades available, you can mix them temporarily. Here are a few points to consider:
Similar Viscosity: Both 5W30 and 10W40 oils have different viscosity characteristics. The numbers represent the oil's viscosity at different temperatures. Mixing them can result in an intermediate viscosity that might not provide optimal lubrication for your engine under all conditions.
Oil Additive Compatibility: Different engine oils may contain different additives, and mixing them can lead to unknown chemical interactions. These interactions may impact the effectiveness of the additives or even result in the formation of undesirable substances.
Dilution: Mixing oils with different viscosities can result in dilution of certain additives. This could affect the oil's ability to protect your engine components properly.
Manufacturer Recommendations: It's always best to follow the vehicle manufacturer's recommendations for the appropriate engine oil grade. They have tested and specified the grade that is suitable for your engine's design and operating conditions.
If you find yourself needing to mix oils temporarily, it is generally recommended to use the same brand and type of oil whenever possible. However, it is advisable to replace the mixed oil with the appropriate grade as soon as possible during the next oil change. If you have concerns or specific requirements, it's always a good idea to consult with a certified mechanic or refer to your vehicle's owner's manual for guidance on the proper oil grade and any mixing precautions.