6 Car Fluids You Need to Check Regularly

6 Car Fluids You Need to Check Regularly

May 05, 2021

Not everyone is technically inclined, so it is understandable if you are not averse to all details in your car. The many fluids that a car uses can be confusing. A small leak somewhere, and then you cannot drive to work. 

It doesn’t matter whether you drive daily or occasionally. A lesson on the types of fluids in a car can come in handy in the most unexpected circumstances. This article will discuss six fluids to check regularly.   

Let’s go!

Engine Oil

Engine oil is used to lubricate the components inside the combustion engines, protect them from corrosion and keep them in cool conditions during driving. 

These parts are mostly metallic, so that friction forces can be significant. Without engine oil, all these parts rub against each other creating friction and heat. The life of the engine is mainly dependent on lubrication because it controls these two factors. 

There are two basic components in any engine oil: base oil and additives. Base oil occupies the most significant percentage, with additives covering up to 10 – 20%. Additives enhance the properties of base oil. 

How Often Should You Check and Change Engine oil?

For your car’s engine efficiency, check the oil monthly or preferably more often, and especially before a long trip. 

The engine oil change intervals may vary from vehicles. If you own an old car, you should change it every 3,000 miles (4,800 km). However, today some modern cars stretch the intervals to 7,500 to 10,000 miles (12,000 to 16,000 km). That is after up to 7 months for an average drive of 50 miles (80 km) per day. So the right answer depends on what type of vehicle you drive and follow your car’s manufacturer maintenance schedule for oil changes. 

It might be necessary to change the engine oil more frequently if the driving conditions are severe. Manufacturers list urban driving, long trips at slow speeds (below 50mph), and regular fast accelerations as some factors that add strain to the engine.

How to Check?

It is easy to check your car’s oil level. While your vehicle is standing on level ground, pull out the dipstick and wipe it on a white clean rag or tissue. Then reinsert it and pull it again to check the level. Look at both sides of the dipstick. If the oil level is below the minimum mark, you need to top up some oil right away. If the oil is smelly (gasoline smell) or dirty, it’s time to change it. 

It is advisable to check the engine oil when the engine is cold. However, some car manufacturers recommend checking when your vehicle reaches normal working temperature. To make sure, you can check your car owner’s manual for specific information.

Transmission Fluid

Your car’s transmission uses a special oil called transmission fluid. This kind of fluid has many functions in the system: lubrication, cooling, and clutch application.

Gear shifting is a tough task for the car, but it is much easier with transmission fluid. The fluid keeps metal parts apart, so there is no wear and tear. If you notice any strange signs whenever you are changing gears, then something is wrong with the system. You need to check the transmission fluid as well as the system immediately. 

There are many types of transmission fluids based on the car model and make. But there is the general categorization: Manual, automatic, and CTV transmission fluids. Knowing which category suits your car is the first step towards choosing the best type. 

How Often Should You Check and Change Transmission Fluid?

The regularity of changing the transmission fluid of a car largely depends on the make and model. So we recommend you check the manufacturer’s recommendations for guidance. In general, most mechanics say that you should check this kind of fluid every year, change it between 30,000 to 60,000 miles (48,000 to 96,500 km) for manual vehicles and 30,000 to 100,000 miles(48,000 to 161,000 km) for automatic transmission cars. Besides, there are also some factors that affect the changing interval such as driving habits, where you live… that you need to change more often.

How to Check

If you are wondering if you can check the fluid yourself, yes, it is possible, mostly for vehicles with transmission dipsticks. All you need is to follow simple guidelines like checking engine oil above. 

Remember that transmission fluid usually has translucent red colour. If its colour turns to dark brown or has a burning smell, you need to change or take it to a service shop for diagnosis. 

For sealed transmission, checking the fluid can be tricky. We would rather you leave that to the technician.

Engine Coolant

Engine coolant is a mixture of distilled water and antifreeze with a ratio of 1:1. This special liquid helps cover both sides of temperature extremes to maintain cooling system integrity. 

Whenever the engine runs, it generates a lot of heat. This heat is enough to damage components within. Engine coolant simply absorbs this heat, travels to the radiator, and then goes back to the engine. The fluid also protects various components of the engine, including plastic and rubber parts. 

Extreme winter temperatures can also damage the engine. If the engine block freezes, it could even crack. In that case, antifreeze helps lower the water freezing point, and your machine isn’t at risk of being cracked anymore. Its anti-corrosion ingredients come in handy during winter. 

When it comes to checking and changing the engine coolant, preventative measures are often recommended. Make a habit of regularly checking the coolant level as indicated in the plastic container in the hood. Top it off if it goes below the minimum level.

How Often Should You Check and Change  Engine Coolant?

It is advisable to check coolant at least every six months, before summer and winter. However, this interval may vary between automakers. 

Although every car manufacturer has their recommended period for engine coolant change, most engines will need a coolant change after running for 100,000 miles (161,000 km). 

How to Check?

Many modern cars have coolant warning lights to alert you if there is any problem with this liquid. All you need to do is open the car hood and find the coolant reservoir tank. It is clear with MIN and MAX marks outside for you to check its level. If the level is below the MIN mark, you need to top it up. Also, check for the coolant leak and cooling system to make sure the engine is in good shape. 

Note that checking the coolant, radiator, or cooling system must be done when the engine is cool.

Brake Fluid

The primary role of brake fluid is to transfer mechanical power from the brake pedal to the drum or disk brakes. This fluid contains a component that pressurizes upon an increase in temperature. With suitable brake fluid, the driver doesn’t have to apply extreme muscle power to slow down or bring a car to a stop.

The operation of braking fluid is all about the basics of fluid dynamics. Of course, “power brake” systems come with a manifold vacuum that makes the brake system even more effective. 

Most modern cars have DOT3, DOT4, or DO5 braking fluid types. The specific fluid in your vehicle will be indicated on the filler cap. Take note of the type since using the wrong brake fluid can cause extensive damage to the brake system. 

Some basic rules of brake fluids are:

  • DOT5 is incompatible with DOT 3 and DOT4
  • Use DOT5 only for a DOT5 car
  • Use DOT4 only for a DOT4 car
  • A car for DOT3 can accept either DOT3 or DOT4

How Often Should You Check and Change  Brake Fluid?

Brake fluid needs to be checked regularly for your safety, and it takes almost no time to do. It is typically changed every 45,000 miles (72,500 km) or every five years, whichever comes first. 

How to Check

The only thing a driver should check is the level. The brake fluid reservoir is translucent, and there are indicators to show its level. If the level is still above the “minimum line,” you don’t need to add brake fluid. If not, then you need to change or refill it. 

In some situations, your brake system probably leaks or needs repair. Maybe the fluid level is so down you can’t even see it. In that case, it might be dangerous to even drive the car to the nearby mechanic. Consider towing the car to the mechanic instead.

Power Steering Fluid

Similar to the brake fluid, the power steering fluid is hydraulic. It transfers mechanical force from the steering wheel to the hydraulic piston within the steering rack. This makes steering the car simpler and smoother. You will mostly find this fluid in cars with hydraulic power steering systems. 

There are several power steering fluid types, so it is important to know which one your car uses. This specification is available on the filler cap or owner’s manual; you can check for specific information. Some vehicles do not have extra specifications. In that case, whatever standard power steering fluid you find will do the job. 

How Often Should You Check and Change Power Steering Fluid?

To maintain the health and safety of your vehicle, you should check the power steering fluid once a month.

Auto experts recommend changing this fluid after 30,000 to 60,000 miles (48,000 to 96,500 km), while some simply say that you should change it every two years. The truth is, there will be no definitive answer to this question. 

However, either 60,000 miles or every two years (whichever comes first), you should change this kind of fluid. Or you can check your owner’s manual for exact information.

How to Check

Checking power steering fluid is similar to the engine oil and transmission fluid. Open the car hood to reveal the power steering container. It is usually clear with a black cap and labeled with the word power steering. There are  MAX and MIN indicators outside the container to show the fluid level. Always make the level is above the MIN mark but not overfilled. 

Remove the cap with the dipstick, then check the fluid as you do with the transmission fluid mentioned earlier.

Windshield Washer Fluid

Who doesn’t enjoy spraying the windshield and whisking away the dirt while on the road? That’s why every car owner needs to have a properly working windshield washer fluid. 

True, this fluid may not be central to a car’s optimal performance, but what happens if a mud splash happens. You want to have adequate fluid. Windshield washer fluid is most helpful during spring because of the melting snow. 

How Often Should You Check and Change  Windshield Washer Fluid?

We recommend you perform this check once per month and refill if necessary. More regular checks may be necessary, especially during winter. The rule of the thumb is to refill if the fluid is 75% consumed. 

How to Check

Check for a plastic container underneath the hood of your car. Is the container full? Get the recommended windshield washer fluid and top up.

There is usually a windscreen symbol on the container. It is easy to tell the amount of fluid remaining because the container is often transparent. Use the manufacturer’s “minimum level” as a guide.


The six fluids covered above are crucial for the optimal performance of your car. With guidance and a little experience, you can perform these checks on your own.

But if you are uncomfortable with the processes, engaging a professional mechanic is better. At the very least, train how to check the fluid levels to help you in decision-making. You never know when a fellow driver on the road will need your know-how.

article by Ryan McCain

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