Here's What Happens If You Put The Wrong Oil In Your Engine

Your car's engine won't immediately fail, make awful noises, or grenade itself from within if you give it the wrong oil. However, using the incorrect oil for long enough can cause premature wear and expensive damage, thanks to excess friction, the formation of varnish on the pistons, and harmful sludge that restricts oil flow. Using the wrong oil not only affects your engine's internal parts, but it could also lead to premature EGR failure, congested particulate filters, or clogged catalytic converters.

That's why using the right type of oil is equally important as adhering to an oil change schedule. However, we totally understand that it's easier said than done, especially when faced with the sheer variety of motor oil types on display at your local auto parts store. Besides choosing between semi-synthetic or full synthetic oil, knowing the right oil specifications (such as the required viscosity and API grades) will go a long way toward making your car's engine healthy, reliable, and durable for the long run.

The oil viscosity is particularly important. Oil that's too thick takes more time to flow, and it may fail to provide adequate lubrication during cold starts or when operating in icy weather. On the other hand, pouring thinner, less viscous oil may fail to provide the lubrication required to protect the bearings, crankshaft, valves, and pistons from heat and friction. Using the wrong oil may induce noticeable symptoms, like pesky oil leaks, poor fuel economy, intermittent cold starting, and a burning smell from the engine.

The good news is that you're not totally screwed if you happen to mix different types of oil, but we're not saying that there won't be far-reaching consequences when doing so. The incompatibility between the two different lubricants will surely degrade the effectiveness of the better one. For instance, if you happened to pour full-synthetic oil into a sump filled with conventional oil, the chemical reaction between the additives and base oils will reduce or diminish the supposed longer life and protection benefits of the synthetic lubricant. 

The bigger issues arise when you mix two oils with different viscosities, as described above. Mixing different types of oil may cause added friction between moving parts or accelerate the formation of harmful carbon deposits. There's no need to worry if you happen to use oil of the same quality and SAE viscosity from different brands. However, mixing oils with different blends and viscosities should be avoided if you want to guarantee the trouble-free operation of your car's engine.

The best way to prevent yourself from using the wrong oil type is to refer to the owner's manual. Lubricants are not a one-size-fits-all affair because the recommended oil for your Toyota may be completely different from what Honda and Ford prescribe for their engines. Honda, in particular, recommends OEM Honda motor oil for every oil change, and it has to do with the oil's compatibility with the specific alloys and metals utilized inside Honda engines.

German automaker Porsche is no different, and the company prescribes Mobil 1 oil for its high-performance vehicles. Porsche also has classic motor oil blends for older sports cars, which are formulated for air-cooled or water-cooled vintage Porsche engines. Oils for gas engines are also different from oils for diesel engines, although there are lubricants that conform to both API CK (diesel) and API SN (gasoline) grades, making them appropriate for both gas and diesel vehicles.

So, what should you do if you pour the wrong oil into your engine? We recommend changing it as soon as possible and before symptoms or possible damage appear. Remember that oil and filter changes are cheaper than engine repairs, and they're certainly more affordable than replacing the motor.