Here's why it's a bad idea:
* Different Cold Temperature Viscosity: The "OW" in OW-20 stands for "0W," indicating a very low viscosity at cold temperatures. This is ideal for starting engines in extremely cold climates. 5W-20, on the other hand, has a higher viscosity at cold temperatures. Mixing them will result in an inconsistent viscosity that may not be optimal for your engine's specific requirements.
* Additives: Motor oils contain various additives to enhance their performance, such as detergents, anti-wear agents, and anti-oxidants. Different oils use different additive packages. Mixing oils could lead to a less effective blend of additives, potentially causing engine wear or reduced lubrication.
* Compatibility Issues: Some motor oils may have different chemical compositions that could cause incompatibility issues when mixed. This could lead to unwanted reactions and potentially harm your engine.
Recommendations:
* Check your owner's manual: Your car's owner's manual will clearly state the recommended oil type and viscosity.
* Use the same oil: Stick to the recommended oil type and viscosity throughout your oil change intervals.
* Consult a mechanic: If you're unsure about the best oil for your engine, consult a qualified mechanic.
Bottom line: It's best to avoid mixing different types of motor oil unless you are absolutely certain they are compatible. Stick to the recommended oil type and viscosity for your vehicle to ensure optimal engine performance and longevity.
