Checking fluids in a car: a complete guide with photos and expert advice

Regularly checking the fluids in a car is like a medical examination for a person: you can ignore it, but the consequences will be dire. The service life of the engine depends on the condition of the oil, your safety on the road depends on the level of brake fluid, and the wrong antifreeze can “kill” the radiator in one winter. At the same time, 68% of car owners, according to the study Autostat 2023, fluids are checked only before maintenance - that is, once every 15-20 thousand km, although some of them require attention every 1-2 thousand kilometers.

In this article we will analyze all critical fluids of a modern car: where to look for them, how to check, what tools are needed and what to do if the level suddenly drops. Let us dwell separately on myths about “eternal” liquids (spoiler: they don’t exist) and typical mistakes that even experienced drivers make. The material is relevant for cars produced from 2010–2026, but most of the tips are also suitable for older models.

1. Engine oil: how to check the level and not drain it completely

Motor oil is the most capricious liquid in a car. Its level and condition need to be checked every 1,000–1,500 km (or before a long trip), even if the manufacturer claims that the oil is “long-lasting”. The fact is that modern engines with turbines and direct injection TFSI or Skyactiv operate at extreme temperatures, and the oil in them ages faster than the marketing claims.

To measure the level correctly:

• 🅿️ Park the car flat surface (even a 5° slope will distort the readings).
• ⏳ Wait 10-15 minutes after stopping the engine - the oil should drain into the pan.
• 🔧 Take out the oil dipstick (usually it is marked with a yellow or orange handle), wipe it with a clean cloth lint-free and push it back in until it stops.
• 📏 Remove the dipstick again and evaluate the level: it should be between the marks MIN and MAX.

If the oil is on the dipstick black, with metal shavings or smells of burning - this is a signal for urgent replacement, even if the mileage has not reached the recommended interval. But if the level of Suddenly fell below MIN, do not rush to top up: first check for any leaks on the engine or under the car (especially after parking).

⚠️ Attention: Never check the oil for “hotness” immediately after a trip - you risk getting burned and getting inaccurate data. And if you add oil, use same brand and viscosity, which is flooded now. Mixing different types (eg. 5W-30 and 5W-40) may cause sediment to form.

2. Antifreeze (coolant): why you can’t ignore it

Antifreeze is responsible for engine cooling and corrosion protection. Checking it is often forgotten until the engine starts to overheat or the heater starts blowing cold air. Optimal monitoring frequency: once every 3–6 months, and a complete replacement is required every 2–3 years (or 60–90 thousand km), even if the fluid looks clean.

Where to look for antifreeze:

• 🔍 In most cars, the tank is located next to the radiator (transparent plastic with colored liquid).
• 📛 There are marks on it MIN and MAX - the level should be between them at cold engine
• 🚫 If liquid cloudy, rusty or flaky - this is a sign that it has not been changed for a long time or that incompatible types have been mixed (for example, G11 and G12+).

Important nuance: antifreeze does not evaporate like water. If its level drops, there is a leak somewhere. Most often the culprits are:

• 🔧 Cracks in pipes or radiator.
• 🔥 Broken cylinder head gasket (then antifreeze mixes with oil - check the dipstick!).
• 🚗 Leaking from under the pump (coolant pump).

3. Brake fluid: why it needs to be changed, even if the level is normal

Brake fluid (DOT-3, DOT-4, DOT-5.1) over time becomes saturated with moisture from the air, which reduces its boiling point. If the fluid “boils” during heavy braking, the brake pedal will become “wobbly” and the braking distance will increase significantly. Manufacturers recommend complete replacement every 2 years, regardless of mileage.

How to check:

1. Open the hood and locate the brake fluid reservoir (usually next to the master cylinder, marked BRAKE FLUID).
2. The level should be between MIN and MAX. If it is lower, add more same brandwhat is poured (mixing DOT-4 and DOT-5.1 acceptable, but not recommended).
3. Assess the color: fresh liquid is transparent with a yellowish tint, old liquid is dark brown.

Critical symptom: if the level drops quickly (for example, a week), this indicates a leak in the brake system. Possible reasons:

• 🛑 Worn brake pads or cylinders.
• 🔧 Damage to brake hoses (especially after winter).
• 🚨 Leak in the brake master cylinder (then the fluid will be on the inside of the wheel or under the brake pedal).

⚠️ Attention: If, after adding brake fluid, the pedal becomes soft or “falls in,” contact service immediately! This is a sign of air getting into the system - the brakes need to be bled.

4. Power steering (power steering) fluid: when to check it and how to replace it

Power steering fluid (PSF) provides ease of rotation of the steering wheel. In modern cars with EUR (electric booster) it is not, but in cars before 2015–2018 (for example, Toyota Corolla, Hyundai Solaris, Renault Duster) it exists and requires attention. Check the level once every 6 months or if the following symptoms occur:

• 🔄 The steering wheel began to rotate tighter (especially at low speeds).
• 💦 Reddish spots appeared under the car (the color of the power steering fluid).
• 🔊 When turning the steering wheel, you hear a hum or squeak.

How to check:

1. Find the power steering reservoir (usually it is white or translucent, with the inscription POWER STEERING).
2. Wipe it with a rag and check the level - it should be between the marks.
3. If liquid has darkened or smells like burning, it needs to be replaced (recommended interval is 60–80 thousand km).

To top up, use the liquid recommended by the manufacturer (for example, ATF Dexron III for many Kia/Hyundai or PSF-4 for Toyota). Do not mix mineral and synthetic fluids - this will damage the power steering pump.

5. Automatic transmission fluid: why its condition is more important than its level

Automatic transmission fluid (ATF) is one of the most “long-lasting” ones, but this does not mean that it does not need to be checked. In CVTs (CVT) and “classic” automatic transmissions, it serves as lubrication, cooling and torque transmission. If you do not change it, the box will begin to “kick” and then completely fail.

The problem is that in 70% of modern machines (for example, Nissan Qashqai, Volkswagen Tiguan) no dipstick to check the level — there is only a control hole, and the fluid can only be checked at a service station. However, there are indirect signs that ATF problems:

• 🔄 Jerks or delays when changing gears.
• 🔥 Burning smell from under the hood (overheated liquid).
• 💧 Red or brown stains under the box.

If your car has an automatic transmission dipstick (for example, in Toyota Camry or Ford Focus), check the fluid like this:

1. Start the engine and warm up the transmission (drive 5–10 km).
2. Place the car on a flat surface, move the selector to position P.
3. Take out the automatic transmission dipstick (usually it is red), wipe it and check the level and condition of the fluid.

⚠️ Attention: If the automatic transmission fluid is blackened or has metal particles, the transmission is already worn out. In this case, a simple replacement ATF may aggravate the problem - diagnostics is required.

Liquid type	Check frequency	Replacement period	Symptoms of a problem
Motor oil	Every 1,000–1,500 km	10–15 thousand km or 1 year	Black color, metal shavings, burning smell
Antifreeze	Every 3–6 months	2–3 years or 60–90 thousand km	Cloudy color, rust in the tank, engine overheating
Brake fluid	Every 6 months	2 years	Dark brown color, soft brake pedal
Power steering fluid	Every 6 months	60–80 thousand km	Stiff steering, noise when turning, leaks
Automatic transmission fluid	Every 10–15 thousand km (if there is a dipstick)	40–60 thousand km	Jerks when switching, burning smell, leaks

6. Washer fluid: why you shouldn’t fill it “by eye”

It would seem, what could go wrong with windshield washer fluid? However, even here there are nuances:

• 🌡️ In winter, use only specialized antifreeze liquid (for example, Liqui Moly Antifrost). Plain water or diluted alcohol will freeze at −10°C and rupture the tank.
• 🚿 In summer, avoid concentrates with aggressive surfactants - they spoil rubber wiper seals and hood paint.
• 🔍 If the fluid suddenly stops flowing, check filter in the tank (it gets clogged with dirt) and washer nozzles (they can be cleaned with a needle).

By the way, in some machines (for example, Audi A4 or BMW 3 Series) washer fluid is also used to clean headlights. If it runs out, you risk being left without light in the rain.

What happens if you add water instead of anti-freeze?

At temperatures below 0°C, water will freeze and can damage not only the reservoir, but also the washer pump (replacing it will cost 3-5 thousand rubles). In addition, ice in the system can block the nozzles, and then the wipers will be “dry,” which impairs visibility.

7. Common mistakes when testing fluids (and how to avoid them)

Even experienced car owners sometimes make mistakes that lead to serious damage. Here are the most common:

1. Checking the oil with the engine running. This is not only inaccurate, but also dangerous - oil under pressure can splash onto hot parts.
2. Ignoring the color and smell of liquids. For example, antifreeze may be at normal levels, but if it has become rusty, it needs to be changed urgently.
3. Mixing different types of liquids. For example, DOT-3 and DOT-5 incompatible, like mineral oil and synthetics.
4. Adding liquid by eye. Overfilling the oil is just as harmful as underfilling it - it creates excess pressure in the system.

Another dangerous myth: “If the fluid doesn’t go away, it doesn’t need to be changed.” In fact, all liquids getting old — the oil oxidizes, the antifreeze loses its anti-corrosion properties, and the brake fluid becomes saturated with moisture. Therefore, even if the level is normal, monitor the timing of replacement.

8. Tools for checking fluids: what should be in the trunk

To independently monitor the condition of liquids, a minimum set of tools is sufficient:

• 🔦 Flashlight (to inspect tanks in the dark).
• 🧴 Clean lint-free napkins (for probes and plugs).
• 🔧 A set of funnels (for accurate topping).
• 📏 Dipstick for checking the oil level (if the standard one is lost).
• 🧪 Antifreeze hydrometer (checks freezing temperature).
• 🔋 Brake fluid tester (measures moisture content).

For deeper diagnostics you can use:

• 🔬 Express tests for oil condition (for example, Liqui Moly Oil Check).
• 📱 Applications for maintaining service history (for example, AutoDoc or MyCar).

If you don't want to carry all these devices with you, at least keep them in the glove compartment spare fluids in small containers (100–200 ml): oil, antifreeze and brake fluid. This will save you on the road if a leak is suddenly discovered.

FAQ: Answers to frequently asked questions

Is it possible to mix oil from different manufacturers if the viscosity is the same?

Yes, you can, but only if both oils have same basis (mineral, semi-synthetic or synthetic) and manufacturer’s approvals. For example, 5W-40 from Castrol and Mobil can be mixed if both are synthetic. However, it is better to avoid mixing and add oil of the same brand that is already filled.

How to understand that antifreeze has lost its properties?

Signs of “old” antifreeze:

• The color has changed (became rusty or cloudy).
• Sediment or flakes have appeared.
• The liquid began to foam when shaken.
• The engine began to overheat more often.

If at least one of these symptoms is present, the antifreeze needs to be replaced, even if the deadline has not yet come.

What to do if brake fluid gets on the body paint?

Brake fluid has an aggressive effect on paintwork. If it gets on the hood or fender:

1. Blot the stain immediately dry with a rag (do not rub!).
2. Wash the area with water and car shampoo.
3. If the stain remains, use body polish.

If the liquid has managed to corrode the paint, local painting will be required.

Do I need to check the fluids in a new car?

Yes, even in a car with 0 km mileage. Here's why:

• The factory may have underfilled the oil or antifreeze (it happens!).
• In the first 1–2 thousand km, running-in, and the oil level may drop slightly.
• Leaks sometimes do not appear immediately, but after 5–10 thousand km.

Check the fluids in a new car after 1,000 km, and then follow the manufacturer's instructions.

Can water be used instead of power steering fluid in an emergency?

Fill in water absolutely not possible - it will cause corrosion in the system and damage the pump. As a last resort, you can temporarily top up distilled water (no more than 100 ml), but then the system needs to be flushed and filled with the correct liquid. It's better to always carry a supply with you. PSF.