Everything You Need to Know About Car Fluids: Oil, Coolant, Brake Fluid, Washer Fluid & More

When was the last time you checked your oil level? If you’re hesitating – don’t worry, you’re not alone. Many drivers underestimate the importance of car fluids. Yet, they are crucial for safety, driving comfort, and the longevity of your car.

In this guide, you’ll learn which fluids a car needs, which ones the garage refills during a service, which ones you should check yourself and how to do it (unless your car already does this automatically), and which warning lights let you know that it’s time to take action.

Which fluids does a car have?

Your car needs more than just petrol or diesel. The most important car fluids are:

• Engine oil – lubricates the engine, reduces wear

• Coolant – prevents overheating

• Brake fluid – ensures reliable braking performance

• Windscreen washer fluid (washer fluid) – for clear vision

• Power steering fluid (in older cars) – assists steering

• Transmission fluid (in some models) – for smooth gear changes

• Fuel – petrol, diesel, or electricity (no oil change needed for electric cars)

• Fuel additive (AdBlue)
  

Which fluids does the garage refill during service?

Usually, the garage will check and top up:

• Engine oil (including oil filter replacement)

• Coolant

• Brake fluid (change usually every 2 years)

• Transmission fluid (depending on the car and interval)

• Power steering fluid (if applicable)
  

💡 In a car subscription like with Carvolution, this service is included – so you don’t have to worry about oil changes & co.

Which fluids should you check yourself – and when?

Even if many things are taken care of during service, it’s worth checking a few yourself – unless your car already does it automatically (and if not: maybe it’s time for a new one – perhaps from Carvolution 😉).

• Engine oil: once a month or before long trips (modern cars often display oil level)

• Coolant: every few months

• Washer fluid: anytime, refill when needed

• Brake fluid: visual check (if reservoir is empty, contact a garage immediately!)
  

💡 How to check engine oil

1. Park the car on level ground, turn off the engine.

2. Wait 5 minutes for the oil to settle.

3. Remove the dipstick, wipe it clean, reinsert it, then remove it again.

4. Oil level should be between Min and Max marks. If below Min: top up oil.
   

💡 How to check coolant

1. Let the engine cool down completely.

2. Locate the coolant reservoir in the engine bay.

3. Level should be between Min and Max marks.

4. If too low: add the correct coolant (see manual).
   

💡 How to top up washer fluid

1. Open the bonnet.

2. Find the washer fluid reservoir with the windscreen wiper symbol.

3. Fill with water and some screenwash until Max mark is reached.
   

Where can you check or refill which fluid?

• Petrol station: top up washer fluid, oil

• At home: check oil and coolant

• Garage: brake fluid, transmission fluid, power steering fluid
  

What should you NOT do yourself?

• Change brake fluid

• Change transmission fluid

• Open coolant cap when the engine is running (risk of burns!)
  

These jobs belong in the garage – incorrect handling can cause damage or injury.

Important warning lights and their meaning

Oil can symbol – low oil pressure or oil level. Stop immediately and check.

Thermometer in water symbol – coolant temperature too high, overheating risk.

Brake symbol – low brake fluid or brake system fault.

Windscreen wiper symbol – refill washer fluid.

Tip: Never ignore warning lights. Stopping right away can prevent serious damage.

What does this mean in a car subscription?

With a car subscription, service, oil changes, and other work on car fluids are included. Still, you should regularly check oil, washer fluid, and coolant – so your car is always ready and safe.

For questions, our Customer Success Team is here for you – by phone at +41 62 531 25 26 or by email at support@carvolution.ch.

Conclusion: Small checks – big impact

Regular checks of car fluids increase your car’s lifespan and keep you safe. In a car subscription, the garage handles most of the work for you – but a quick look under the bonnet can save you expensive repairs.

Don’t have a subscription yet but want to stop worrying about checking, topping up, or changing car fluids? Discover our cars now and learn about all the benefits of a car subscription.