top of page
  • Writer's picturejianmei huang

Auto Fluids 101: Everything Drivers Need to Know

Updated: Feb 20

Have you ever wondered what makes your car tick? Imagine your vehicle as a living, breathing entity. Just like us, cars need a variety of fluids to stay healthy and perform at their best. In this article, we'll dive deep into the world of automotive fluids, exploring their types, functions, and how to check them. Whether you're a seasoned driver or a newbie on the road, understanding these essentials can save you from unexpected breakdowns and hefty repair bills.


Engine Oil

Think of the engine oil as the lifeblood of your vehicle, a vital fluid that ensures the heart of your car beats smoothly and efficiently. Just as the blood in our bodies carries oxygen and nutrients to our cells, engine oil lubricates the engine's moving parts, reducing friction and wear. It also plays a crucial role in cooling the engine by carrying heat away from the moving parts and preventing a buildup of harmful substances inside the engine compartment.

But how do you ensure that this lifeblood remains pure and effective? The key is in regular checks and timely changes. Checking the oil level is straightforward: park your car on a level surface, wait for the engine to cool down, then locate the dipstick. Pull it out, wipe it clean, reinsert it, and pull it out again to check the oil level. The oil should be between the "min" and "max" marks on the dipstick. Moreover, observe the oil's color; it should be amber to light brown. Dark, gritty, or excessively thick oil can indicate the need for a change.

Changing your engine oil at manufacturer-recommended intervals is crucial. Over time, oil breaks down and loses its viscosity and lubricating properties, leading to increased engine wear and potential damage. Remember, a well-lubricated engine is a happy engine, leading to a smoother ride and extended vehicle life.


The coolant, or antifreeze, is the guardian against extreme temperatures, ensuring your engine operates within a safe temperature range. It’s a magical potion, composed of water and antifreeze, that circulates through the engine and radiator, absorbing heat and preventing the engine from overheating. But its role doesn't end there; coolant also prevents freezing in cold climates, protects against corrosion, and helps maintain optimal engine performance.

Checking the coolant level is as simple as popping the hood and locating the coolant reservoir. This transparent container is usually marked with "min" and "max" lines to indicate the proper coolant level. It's essential to check the coolant when the engine is cold to avoid injury from escaping steam or hot fluid. If you find the level low, top it up with a mixture recommended by your vehicle's manufacturer. However, consistently low coolant levels might indicate a leak, requiring immediate attention to prevent engine damage. A professional car scanner can also help you diagnose condensation problems, such as the ANCEL X7.

Regular coolant changes are also vital. Over time, the protective additives in the coolant break down, diminishing its ability to prevent corrosion and maintain optimal engine temperature. Following your vehicle manufacturer's recommendations for coolant change intervals ensures your engine stays cool under pressure, extending its life and performance.

Transmission Fluid

Transmission fluid is the unsung hero that ensures the smooth operation of your car's transmission. Like a skilled conductor leading an orchestra, it ensures that the various components of your car's transmission system work in harmony, providing smooth gear shifts and reliable performance. This fluid serves multiple purposes: it lubricates the transmission's moving parts, helps to keep the transmission cool, and even acts as a hydraulic fluid in automatic transmissions, facilitating gear shifts.

To check the transmission fluid, you'll often need your car to be running and warmed up, parked on a level surface. For most vehicles, checking the transmission fluid involves pulling out the transmission dipstick (similar to checking your engine oil but with the car running), wiping it clean, reinserting it, and then checking the level and color of the fluid.

The fluid should be a bright red or amber color and should not smell burnt. If it does, or if the level is low, it might be time for a change or top-up.

Transmission fluid doesn't need to be changed as frequently as engine oil, but it's crucial not to neglect it. Over time, the fluid can degrade or become contaminated, leading to sluggish gear shifts, decreased fuel efficiency, and even transmission damage. Following your manufacturer's recommended service intervals can prevent these issues and help ensure that your transmission continues to operate smoothly.

Brake Fluid

Brake fluid is a vital component of your car's braking system. Acting under the principle of hydraulics, it transfers the force from your brake pedal to the brake pads, allowing you to slow down or stop your vehicle effectively. Because of its critical role in vehicle safety, maintaining the right brake fluid level and quality is non-negotiable.

To check the brake fluid, locate the brake fluid reservoir in your engine bay. The level should fall between the "min" and "max" marks on the side of the reservoir. If the fluid is below the "min" line, it's time to add more. However, it's also essential to check the color of the brake fluid. Fresh brake fluid should have a clear to slightly amber appearance. If it appears dark or murky, it's an indication that it's absorbing moisture and contaminants over time, which can significantly reduce its effectiveness and potentially damage the braking system.

Changing the brake fluid at intervals recommended by your car's manufacturer or more frequently if you frequently drive in harsh conditions, can help maintain your brakes' responsiveness and reliability. It's a small but critical step in ensuring your safety and that of others on the road.

Power Steering Fluid

Power steering fluid is what allows you to steer your vehicle with minimal effort. This fluid works within the power steering system to facilitate the transfer of steering input from the steering wheel to the wheels on the road. Without it, steering would require much more force, especially at lower speeds or when stationary.

Checking the power steering fluid regularly is simple and can prevent steering problems. The reservoir is usually labeled and can be found easily under the hood. There should be level marks on the outside of the reservoir or a dipstick attached to the cap. Like other fluids, the power steering fluid should be within the recommended levels and clean. A dark color or a burnt smell can indicate it's time for a change.

Maintaining the power steering fluid not only ensures smoother steering but also protects the components of the steering system from wear and tear. Neglecting this fluid can lead to harder steering, increased wear on your tires, and eventual failure of the steering system components, leading to expensive repairs.

Windshield Washer Fluid

Windshield washer fluid might seem less critical compared to the other fluids mentioned, but it plays a significant role in maintaining visibility while driving. This fluid, stored in a reservoir and used through jets to clean the windshield, is essential for removing dirt, bugs, and other debris that can obstruct your view while driving.

Checking and refilling the windshield washer fluid is perhaps the simplest of all the tasks. The reservoir is usually easy to find and often marked with a windshield/water symbol. There's no dipstick for this one; just make sure the reservoir is full by topping it up with a suitable windshield washer fluid. In colder climates, ensure the fluid contains antifreeze properties to prevent freezing.

Regularly checking and topping up your windshield washer fluid can seem like a small task, but it's crucial for safe driving. Good visibility is paramount, and whether you're dealing with mud splashes or winter salt, having a full reservoir of windshield washer fluid means you're always ready to clear your view.

Air Conditioning Refrigerant

Imagine entering your car on a blistering summer day, turning on the air conditioning (AC), and being greeted with cool, refreshing air. This comfort is made possible by the air conditioning refrigerant, a key fluid that absorbs heat from your car's interior and expels it outside, reducing the inside temperature to a more comfortable level. Unlike other automotive fluids, the refrigerant operates in a closed system and typically doesn't require regular topping up unless there's a leak.

Detecting issues with your AC refrigerant often starts with noticing your car isn't cooling as effectively. Because checking and refilling refrigerant requires specialized equipment and knowledge of the AC system, this task is best left to professionals. They can also check for leaks and repair them, ensuring your system remains efficient and effective. Regular AC checks, especially before the peak of summer, can ensure your comfort and prevent more significant issues down the line.

Differential Fluid

The differential fluid is crucial for vehicles with rear-wheel drive, four-wheel drive, or all-wheel drive systems. It lubricates the differential, a component that allows the outer drive wheel to rotate faster than the inner drive wheel during a turn, ensuring smooth and stable handling. Without proper lubrication from the differential fluid, your vehicle's differential would wear out prematurely, leading to poor handling and potentially costly repairs.

Checking the differential fluid involves locating the differential case and its fill plug. However, because this task can be more involved and requires lifting the vehicle, it's often checked and replaced during regular vehicle maintenance or service. Like other fluids, the differential fluid should be clean and at the appropriate level to ensure it can effectively reduce friction and wear in the differential. Following your vehicle's maintenance schedule for differential fluid changes can prevent wear on the gears, ensuring smooth and responsive handling.


Maintaining your vehicle's essential fluids is akin to ensuring a well-oiled machine—literally. From the engine oil that keeps your car's heart beating to the brake fluid that ensures your safety on the road, each fluid plays a pivotal role in your vehicle's performance, safety, and longevity. Regular checks and maintenance not only prevent unexpected breakdowns and costly repairs but also provide peace of mind, knowing your vehicle is in top condition.


How often should I change my engine oil?

Change intervals vary by vehicle and oil type; newer models with synthetic oil can often go 7,500 to 10,000 miles. Check your owner's manual for specific recommendations.

Can I top up my coolant with water in an emergency?

Yes, in an emergency, you can temporarily add distilled water, but it's crucial to restore the proper coolant mixture as soon as possible.

Why is it important to use the correct type of transmission fluid?

The wrong fluid can cause transmission issues due to improper lubrication and friction. Always use the manufacturer-recommended type.

Recommended Similar Articles

16 views0 comments


bottom of page