So, You Just Mixed Synthetic And Regular Oil

So, you mixed synthetic oil and conventional oil. You screwed up, and now you’re wondering if what you did will have catastrophic consequences. Whether it was a simple accident or if you did it on purpose, you now have two kinds of oil in your crankcase instead of one. Are you in trouble? Have you done irreversible damage to your car? Is your engine toast?

In a word? Nah. Despite decades of online chatter equating conventional oil and synthetic oil with matter and antimatter, they are both, at the end of the day, petroleum products. We know that conventional oils are one hundred percent, all-natural, fully organic dinosaur squeezins, right? Well, synthetic oils — despite being built in a lab out of various lubricants, detergents, protective polymers, and other concoctions — all contain as their core ingredient a small amount of high-quality conventional oil. This means that conventional oils and synthetics are largely compatible, but in the way that, say, horses and donkeys are compatible. When you mix them you get a hybrid that exhibits both the good and bad qualities of each parent, as it were.

If you have to mix conventional oils and synthetics, or if you use a bottle of synthetic oil to top off a particularly hungry engine, you’re not going to do any damage to your engine. Not in the short run, at any rate. See, the only thing that really happens when you mix the two kinds of oil is that the conventional oil dilutes the synthetic oil and reduces the effectiveness of all the additives mixed into it. It’s not going to instantly corrode everything inside your engine, or turn into chlorine gas or anything, but it will reduce the synthetic oil’s lifespan and performance.

So, yeah, mixing synthetic and conventional oils is mostly harmless. Just make sure you get your oil changed sooner rather than later because the hybrid oil won’t last as long as pure synthetics. Oh, and to add to that, you can absolutely switch back and forth between synthetic oil and conventional oil if you need to, it’s not going to hurt anything in your engine.