Checking and changing your car fluids: the essential guide
#obdelevenChecking and changing your car fluids: the essential guide

With combustion-powered vehicles running a fair share of systems that rely on fluids, making sure that your car has enough is crucial to keep your vehicle running for a long time. In addition, the efficiency of your engine, transmission, and even brakes, relies on having enough oil or fluid in the respective reservoirs – and running an inefficient vehicle in this economy? Not an idea that many would sign up to.

Nevertheless, checking the fluids, whether it would be the engine oil or the washer fluid differs from car to car, especially between two manufacturers if they are not from the same group. The Volkswagen Group (VAG), for example, uses a single platform for certain types of vehicles – such as the MQB platform for the Audi A3, Seat Leon, and Volkswagen Golf, among others – while larger vehicles, such as the Audi A5 or the Audi A7, are based on the MLB platform. As a result, each car from different manufacturers will have different placements of all the fluid tanks under the bonnet, which means it is best to consult the manual of your car not only for the place where you can find your dipstick but also for the intervals when you need to change the respective fluids.

Checking and changing your engine oil

One of the most obvious fluids to check and change during and following a purchase of a second-hand vehicle is engine oil. You should also regularly change and check your oil if you want to make sure that your car runs for a long time.

Checking the level of your oil is very straightforward. Open up the engine bay, check for the dipstick and pull it out, clean it with a tissue or something else, and then repeat the procedure without wiping anything off. Check the level, which should be between the MIN and MAX lines, and if needs be, fill up with more oil. It is recommended to do the procedure once your engine has cooled off for at least 10 minutes, as the readings might be a bit incorrect if the lubricant running through your engine is still warm.

The consistency and cleanliness of the oil are as important as the level. If the oil is sticky and not smooth or you notice metal particles or other debris – better examined once you dump your oil through the sum plug – there might be something very wrong inside your engine and you should see a mechanic for any potential leaks or damage within the block.

If you wish to change your oil by yourself, the procedure is not that difficult and requires only a few items, including an oil drip tray or a drum drain pan, a degreaser, a new oil filter, and – following a consultation with your user manual – new oil for your engine. First things first, lift your car, making sure that it stays stable while you work below it, place the drip tray/drum drain pan below the sump and unscrew the sump plug. Do so carefully, though, as due to the built-up pressure in the sump, oil can spray everywhere and anywhere. Once it drains out, clean out the plug with a degreaser and screw it back in. Be mindful that some oil sump plugs are one-use only, meaning that you have to replace them as you change your oil.

It is recommended that if you do change your oil, as usually these intervals are intertwined, to change your oil filter as well. Typically, located somewhere at the bottom of the engine, unscrew it carefully and – following a brief spray down of the filter hole and housing with a degreaser – put your new filter with a new seal ring back in its place and fill your car with new oil. You can also reset your oil service intervals with OBDeleven, which is showcased in the video below:

Checking and replacing your coolant

Checking and changing your oil is a procedure that most of us drivers have experienced or witnessed in our lives. With coolant or antifreeze, the situation is much different, as the interval is much higher.

But examining whether your car has enough coolant is much easier and is done visually. Open up your engine bay and you should see a white transparent reservoir – typically with a blue cap – that also has a MIN and MAX indicator. If your coolant is too low fill it up carefully and make sure it does not touch your skin. Most modern cars have sensors that will indicate whether you have enough coolant/antifreeze in the reservoir, allowing you to avoid the procedure of opening the hood and getting your hands dirty.

You will have to get your hands dirty if you want to dump and replace the coolant yourself – check the intervals in your user manual – as it is a bit more complicated compared to a typical oil change procedure. Critically, do not attempt to change the coolant without the engine and radiator being completely cool, as it is a serious safety hazard for you and your car. First things first, make sure your heater core is opened up by turning up the maximum temperature setting and running your car for a brief moment. Once again, be careful not to work with coolant when if your engine is warm.

Continue the procedure by opening up the radiator cap and just to be safe, cover up the hole to prevent any unwanted fragments from reaching your car’s cooling system. Place a drip tray beneath your car and open up the drain plug, which is typically somewhere around the radiator. Once the coolant is gone from there, move the drip tray beneath the engine and drain any remnants of your antifreeze from the block itself by loosening the engine drain bolt. A good idea before reinstalling both plugs is to clean the hole with some degreaser and apply thread sealant on the two bolts just to make things easier in the future.

Remove your coolant reservoir, clean it, and put it back in its place. Fill it with enough coolant without overdoing it. The correct coolant/antifreeze mix is referred to in your owner’s manual, as well as the amount of coolant you should pour into the radiator. Once you have done that, now comes the time-consuming part, as you will have to “remove” all of the air from the system. You can insert a funnel into the radiator to prevent any coolant from spilling all over your engine bay, as well as the ground. Once you start the engine the fluid will begin to bubble inside the funnel or the radiator hole, which means that the system is cleaning itself of any excess air. The process can take up to half an hour and you can use that time to check for any coolant leaks beneath your car.

Once it stops bubbling, turn off the engine and check the reservoir and fill it up if that needs to be done. Replace the radiator cap and turn the engine once again to check for any potential problems or leaks throughout the engine bay and below the power plant. If all goes well – congratulations, you just replaced your coolant!

Replacing your windshield washer fluid

The good news regarding the windshield washer fluid is that it is the easiest to maintain out of this list. While it might be hidden deeper in the engine bay or under some plastic covers, your car will always indicate that you ran out of it. The first sign will be that once you push or press the windshield wiper lever, nothing will come out, providing an indication that you ran out of fluid.

Another sign will be the windshield washer fluid dashboard light, indicating that you ran out of it. Equipped on, dare I say, all modern cars – it can be disabled with OBDeleven One-Click Apps as well – it will warn you that you ran out of the liquid and that you need to top up.

The reservoir cap, which is also typically blue, will be found at the front of your engine bay, where you can refill it easily. However, be mindful that if you live somewhere with multiple seasons, winter and summer windshield washer fluid has a different chemical composition. While the former will allow you to clear the ice and snow more easily from your windshield, the latter is more suited to mop up all of the bugs that have fallen in a one-sided battle against your car’s front.

Still, if you have recently filled up with washing fluid and it disappears much quicker than it is supposed to, you ought to pay a visit to a mechanic or find the leak yourself.

Where to check the power steering fluid?

One of the most underlooked areas where car technology has moved forward is the way we operate the wheel. Parallel, perpendicular, or angle parking would not be the same without the current power steering systems in place since the mid-20th century. Simply put, power steering works with the help of the pump that pushes hydraulic fluid to apply additional pressure on the wheels once you turn the oval thing found inside your car.

However, as research and development continued to perfect the vehicle, electric power steering (EPS) has become more widespread throughout car makers’ lineups. EPS provides a major advantage as it does need the engine to operate, which in turn does not consume fuel. Despite being electrically driven, they are also easier to maintain and do not require any fluid, for starters.

In the case that you are driving an older car with a hydraulic power steering system, one of the first indicators ¬– without a glance into the engine bay – is a steering wheel that is much more difficult to turn. Once you open up the hood and check for the location of your power steering fluid reservoir. The process to check the level of the fluid inside is similar to checking the level of engine oil, except the dipstick is much smaller. Pull it out, wipe it off, dip it into the reservoir and pull it out again and check whether the fluid sits between MIN and MAX indicators. 

As always, referring to the owner’s manual, fill the car with the recommended power steering fluid and check for any potential leaks for the next few drives you go on if the level did dip below the MIN indicator.

Checking and replacing brake fluid

Another reservoir that is found under the bonnet, the place to fill your car with brake fluid sits somewhere near the engine. On the seventh-generation Volkswagen Golf, for example, the reservoir is just slightly behind the engine, and it has two indicators, MIN and MAX. You should be able to determine whether there is enough material there by just looking at the small tank.

An indication that there might be a lack of brake fluid could also be a very lackluster performance of your brakes. The purpose of brake fluid is to provide pressure to the brake pads to clamp onto the rotors once you step on the pedal. If that does not happen the very moment you step on it, though, it is time to take a look at your fluid levels and check for any potential leaks. There also might be an issue with your rotor or your brake pads, even if the level of brake fluid is fine, or your brakes might be underperforming due to the age of the fluid, contamination, or line failure. 

Furthermore, you should check your owners and workshop manual for the intervals to change your brake fluid, which can range from every two to three years, to doing so even more often if you are using your car's braking system more intensively.

Whatever the issue might be, address it as soon as possible, as the ability to stop your car is crucial to the safety of every road participant.

Taking care of transmission fluid

Akin to the oil found in your engine, the purpose of the liquid is to lubricate everything in the transmission to prevent metal parts from rubbing into each other, resulting in long-term damage and a tearful payment at a workshop.

Transmission problems, whether you are driving a manual or automatic, can also stem from the lack of fluid or its age, or if it has foreign object debris in it. Nevertheless, you can check the state of your transmission fluid with a dipstick. Most cars, particularly automatics, will not have one, though, which means that you will not be able to just check the level and state of fluid on your driveway. In case you are having issues with your transmission, it would be a good idea to get your car to a mechanic for them to check it out properly and resolve any issues correspondingly.

Whatever the fluid might be, remember that they are crucial for your car to run efficiently and safely, protecting you and others around you. If you are unsure about a problem you are having with your car, you can always use the diagnostics features of OBDeleven, which can showcase a problem with your engine, transmission, or any other system on your car. Live Data and Charts can also provide more context to an issue, such as if your transmission is overheating or is unable to reach the optimal working temperature, and subsequently, has problems changing gears while you drive.