What Happens If You Put the Wrong Fluids In Your Car? 

Car ownership is a responsibility that requires a little knowledge to be successful. Safe driving, paperwork, and car maintenance are all vital parts of owning a car. While the first two are required by law, there are many people that neglect their car’s service needs. We all know the ones who go thousands of miles beyond the recommended oil change and who have no idea how to check their oil, put air in their tires, or change a flat. There are many things that can go wrong when one of these people decides to add fluid to their vehicle. If they put the wrong fluid in the wrong location, it could cause some problems. 

There are also instances in every shop where a technician or mechanic makes a mistake and puts the wrong fluid in the car they are servicing. Accidents happen in each scenario, but it is important to fix the issue before it creates a bigger problem. If you are familiar with either one of these situations, you may need to know what happens if you put the wrong fluids in your car.

Check the owner's manual for the recommended fluids to use on your car.


Different vehicles use different types of oil. Oil grades range from a thin 0W-16 to diesel oil as a 15W-40. Putting the wrong weight of oil in your car can create problems with lubrication and heat retention. These can create a sludge, be hard on your oil pump, and eventually create engine damage. Using the correct type of oil is important to protecting your engine. 

If something other than oil is put into your car’s engine, it is extremely dangerous and will cause damage almost immediately. Internal engine damage could be very costly or require an entire engine replacement. 

Transmission Fluid

Transmission fluid is important and has many uses within your car. It cools, lubricates, and is a hydraulic fluid that shifts the gears while you accelerate. There are different types of transmission fluid for each car, such as Dexron for General Motors or Mercon in Ford. Putting the wrong transmission fluid in your car can damage your transmission and its gears. The transmission may drive for a limited amount of time with the wrong fluid, but this doesn’t mean all is well. The wrong fluid won’t lubricate or redirect heat like intended and will cause irreversible damage over time. 

Brake Fluid

Brake fluid is another important fluid that requires a certain type in each vehicle. DOT 3 and 4 are the two most common brake fluids. The majority of vehicles require DOT 3, however, DOT 4 can be used in these systems. 

Unfortunately, the reverse is not true and you should flush your brake system if you put DOT 3 in a car that requires DOT 4. The boiling point is different in these fluids, meaning the DOT 3 will not effectively operate in the newer system that requires DOT 4. This can cause damage and become a safety problem if your brakes quit working properly. 

There is also a DOT 5 fluid, which is in high performance vehicles or ones that must endure a large amount of heat. This is an uncommon fluid and is made of a different chemical compound. 

Power Steering Fluid

While some cars use an electric power steering system, others use fluid as a hydraulic system to give you power steering. Many General Motors products take a manufactured power steering fluid, while cars like Ford and Toyota use an automatic transmission fluid. Putting the wrong fluid in the wrong system can result in your power steering pump making noise and being difficult to steer. It will also begin to damage other components of the system, and could ruin your power steering rack. If the wrong fluid is put into your power steering system, flush it out immediately. A power steering rack replacement can cost close to a thousand dollars!


Antifreeze, also known as coolant, is used to cool your engine. This stops it from overheating and warping or ruining parts. Antifreeze is also used to heat the cab. Your car’s heater system passes hot coolant through the heater core and blows air over it and into the vents. Putting water in your car instead of coolant is not uncommon, but can be dangerous. People sometimes do this to save money on coolant if there is a major leak somewhere in a hose or radiator. If the temperature drops too low, the water could freeze in the car and ruin vital parts of your engine. 

Using the wrong coolant or putting water in your car can cause your cooling system to disintegrate prematurely. Putting the wrong fluid in your car breaks down its parts prematurely and could also cause overheating. Water will create rust within your water pump or radiator and make sludge throughout the engine. This will cause internal engine damage and could be a very costly repair. If the wrong fluid or water is put into your coolant system, have a mechanic flush the system before it causes excessive damage. 

Windshield Washer Fluid

Windshield washer fluid is used to keep your windshield clean when it acquires dust or bugs on the highway. While using something other than windshield washer fluid won’t ruin your engine, it could cause some serious headaches. 

Using regular water could freeze if the temperature gets too cold, causing damage to the windshield washing system. If you accidentally put coolant or another substance in your windshield washer reservoir and use it, the oily substance on your windshield will create serious visibility problems.  

Put the Right Fluids In Your Car

People pour the fluids into vehicles, and people make mistakes. If a mistake happens and the wrong fluid is poured into your car, it is important to drain that fluid and replace it with the correct one. This could be as simple as changing the oil again or require a more complex fix such as an entire coolant flush. Putting the right fluids in your car is vital to get the best performance and endurance. 

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