Here's an article from the Engine Oil Journal: Can You Mix Engine Oil Brands. In summary:
"While it’s not catastrophic to mix engine oil brands occasionally, consistency is key for long-term engine health. Using the same brand and type of oil ensures that your engine gets the full benefit of a carefully engineered formula. It helps maintain optimal lubrication, keeps internal parts cleaner, and provides better protection under stress.
So, while you can mix oil brands, it’s best to do so only when necessary. When it’s time for your next oil change, stick with one trusted product that meets your car manufacturer’s recommendations. That way, your engine gets the consistent care it needs to stay strong, efficient, and reliable."
"While it’s not catastrophic to mix engine oil brands occasionally, consistency is key for long-term engine health. Using the same brand and type of oil ensures that your engine gets the full benefit of a carefully engineered formula. It helps maintain optimal lubrication, keeps internal parts cleaner, and provides better protection under stress.
So, while you can mix oil brands, it’s best to do so only when necessary. When it’s time for your next oil change, stick with one trusted product that meets your car manufacturer’s recommendations. That way, your engine gets the consistent care it needs to stay strong, efficient, and reliable."