Beyond fuel: the other fluids that move your vehicle

Más allá del combustible
08 July 2025

When we think about what makes a car or a motorcycle work, fuel is usually the first thing that comes to mind. However, there are a number of liquids and fluids that also play a critical role in getting everything working properly. 

From keeping the engine at the right temperature to ensuring you can brake safely, these fluids are the lifeblood of your vehicle's performance and safety. We've put together this quick guide to explore each of them in detail, explaining their function, importance, and how to care for them properly.

Engine oil: the heart of the system

Engine oil is undoubtedly one of the most important elements for the operation of any vehicle. Its main task is to lubricate moving parts such as pistons, valves, and bearings, reducing friction between them. This prevents premature wear and helps maintain engine efficiency.

In addition, the oil acts as a cleaning agent, trapping dirt particles and residues generated by combustion. It also helps to dissipate the heat generated during engine operation, preventing parts from overheating.

Over time, the oil loses its properties due to heat and the accumulation of particles and residues, so it is crucial to change it regularly according to the manufacturer's recommendations. For this reason, it is very important to check the oil level regularly and be on the lookout for signs of lubrication-related problems.

Coolant: the temperature regulator

A vehicle's engine generates a large amount of heat while running. If this temperature is not controlled, it can cause serious damage, such as overheating or even deformation of internal components. This is where coolant, also known as antifreeze, comes into play.

It's a fluid that circulates through the cooling system, absorbing heat from the engine and dissipating it through the radiator. In addition, the coolant contains additives that prevent internal corrosion, protect against the formation of deposits, and ensure that the vehicle operates efficiently in both hot and cold climates.

Like oil, coolant does not last forever. Over time, the protective properties degrade, which can compromise their capabilities. Therefore, it is advisable to check it regularly and replace it as prescribed by the manufacturer's instructions.

Brake fluid: an ally to keep you safe

Your vehicle's hydraulic braking system is completely dependent on brake fluid to function properly. This fluid transfers the force you apply to the brake pedal to the brake calipers or cylinders, allowing the pads to press the discs or drums and stop the vehicle.

One of the key characteristics of brake fluid is its resistance to heat. During braking, a large amount of heat is generated due to friction, so the fluid must maintain its effectiveness at high temperatures. 

As its use is prolonged, this fluid can absorb moisture from the environment, which reduces its boiling point and can cause failures. So, if you notice that the brake pedal is softer than usual or that you need more distance to stop, it could be a sign that the brake fluid needs immediate attention.

Remember: a braking system in good condition is key to your safety and that of those around you. For this reason, it is essential to check your brake fluid regularly and replace it when necessary.

Transmission oil: what makes shifting gears possible

The transmission, whether manual or automatic, is responsible for transferring power from the engine to the wheels. For this to happen smoothly and efficiently, it needs to be well lubricated, and this is where transmission oil comes in.

In manual transmissions, this oil lubricates gears and other internal components, reducing wear and ensuring accurate gear changes. In the case of automatic transmissions, the transmission fluid performs additional functions, acting as a hydraulic medium to facilitate gear changes while also cooling the system, as these transmissions generate more heat.

If you experience difficulties when shifting gears, strange noises, or vibrations, it could be a sign that the transmission oil is low or deteriorating. Changing it according to the manufacturer's specifications is essential to prevent damage and prolong the life of your vehicle.

Power steering fluid: comfort and control

In vehicles with hydraulic power steering, this fluid makes turning the steering wheel easier, making driving more comfortable and precise. Without it, turning the steering wheel would require much more effort, especially at low speeds or when maneuvering in confined spaces.

Power steering fluid also lubricates system components, reducing wear and preventing damage. Strange noises when turning the steering wheel or its stiffness may be signs that the fluid level is low or needs to be replaced.

Windscreen washer fluid: clear visibility

Although it does not directly affect the mechanical performance of the vehicle, wiper fluid is essential to ensure good visibility on the road. It is designed to remove dirt, insects, mud, and other debris without damaging the glass or brushes.

A clean windshield doesn't just keep your vehicle looking spiffy: it is also crucial for safety, especially in adverse weather conditions. Make sure to refill the tank with a suitable and quality liquid. Otherwise, it will freeze in winter or bacteria will build up inside.

Some final tips

As you have seen, lubricants play a vital role in the operation of your car or motorcycle, so ignoring their maintenance can lead to serious problems, from breakdowns to risks to your safety. Therefore, it is essential to check them regularly, follow the manufacturer's recommendations, and use high quality products, as they prolong the life of the vehicle. 

At Repsol Lubricants, we offer you a wide range of products designed to ensure maximum performance and protection. If you are not sure what lubricant or fluid your vehicle needs, use the search engine on our portal to find the right one for you: just type in the model or license plate. In addition, if you have technical questions or need personalized advice, our team of experts is ready to [u]help — just fill out the contact form!