What happens when you overfill your car's engine oil

Engine oil as many may know it is the lifeblood of a motor, it is there to keep all the parts happy and lubricated as well as to protect these parts from premature wear and tear by creating a thin protective film. While oil for an engine is generally good, too much or too little of it can also be detrimental to its lifespan. With that said, we answer the question: what happens when you overfill your car’s engine with too much oil?

Before we get into why too much oil can be a bad thing for your car’s engine, we first need to understand what it does while it’s in the motor. Oil will typically be refilled via the oil cap located on top of the crankcase in your car’s engine. Once the oil enters the motor it settles in the oil pan when it is not running. When you start your engine, the oil will begin to circulate it and through filters lubricating all of the parts.

When there is too much oil in your car’s engine, there is a chance that the fast-moving crankshaft can come in contact with oil and aerate it. This causes the oil to foam or froth and inhibits its ability to protect and lubricate the moving parts. Aside from this extra oil also creates excessive pressure inside the motor that escapes through the gaskets and seals. This in turn causes leaks and more problems for you as your motor will no longer be able to retain its oil. If one or more of these gaskets or seals fail it could lead you to costly repairs.

When figuring out why your car’s engine has too much oil in it, the usual suspects are normally either you or your mechanic, as one of you could have overfilled the crankcase when topping off the engine oil after an oil change. Excess oil can also be attributed to failing to properly drain the old engine oil from your car or by adding too much oil to the new filter as well. Either way, these issues can usually be attributed to human error.

Another possible reason why there is too much oil in your car’s engine is because of other combinations of fluids. These can be a mixture of oil and fuel or oil and coolant due to a faulty or failing gasket. In this case, it might boil down to the part failing naturally, or it’s a result of something else. In any of these cases, the excess of diluted oil can cause some serious damage to your engine. 

The quickest way to do this is to check the dipstick of the engine. There you will be able to make a quick diagnosis if there is too much or too little oil inside the motor. Ideally, the oil level should be at the middle part of the dipstick measurement segment. This gives you some room to add more oil if needed if your car starts leaking oil. It’s also advisable to check your oil levels frequently and to consult your owner’s manual for specific guidance on how to check your car’s dipstick as designs may vary. 

Other indicators are if your car’s exhaust is producing blue smoke or has a burning oil smell coming from the exhaust pipe. Another indicator is high oil pressure if your car has a gauge for this. You can also tell if a car has too much oil in the engine by paying attention to how the motor runs. If it’s running rough and there is oil on the spark plugs this could be an indication of too much oil or a different mechanical problem. Either way, it’s best to have your vehicle serviced immediately if you notice this happening. 

The only way to remove excess oil from your vehicle’s engine is to drain it from the motor. You can do this by sending it to a shop or by draining the oil yourself. If you don’t mind getting down and dirty you can easily remove the drain plug at the bottom of the oil pan and completely drain the excess oil yourself. It is important to note that you will need to replace the oil filter as well and refill your engine oil on your own specified by the owner’s manual. It can be a messy process and you will need a place to store the old oil in but it can save you a couple of pesos in the process. Conversely, you can just send your vehicle to a service center to have them do the job for you. You can also have your vehicle towed there if you are worried about causing damage to your vehicle by running the engine.