Why using the correct fluids is so important

Beware when topping up fluids at fuel stations

Reuben Van Niekerk
Consumer advice
vehicle maintenance

Modern day vehicles rely on a variety of fluids to operate optimally. Using the correct fluids is critical to the operation of your vehicle and not doing so could be life threatening, leave you stranded on the side of the road or lead to catastrophic failure of expensive components.

Visiting a petrol station and having your tyres, oil and water checked is a common occurrence, but it is critical that you pay attention to what the attendant is adding to your car as the incorrect fluids could have serious effect on the reliability of your vehicle.

Clearly communicate with the attendant whether you would like petrol or diesel and which grade and make sure that they fill your vehicle with the correct type and grade of fuel. Modern vehicles operate at extremely tight tolerances and using the incorrect grade of fuel can severely affect performance or even cause damage to components in the fuel system.

If you realise that diesel has been added to your petrol vehicle or the other way around, do not attempt to start the car or even put the key in the ignition as this will activate the fuel pumps. With assistance of the forecourt manager you will need to get your car transported to a workshop where the tank can be correctly drained and flushed.

You should never check your cars coolant level when the vehicle is hot, so doing so at a fuel station is actually not a good idea. The system is under pressure and more water is likely to leak out than what the attendant can top it up with.

The coolant systems of modern cars utilise specialised coolants, some which contain glycol and others, which are glycol free and mixing the two different types can have a detrimental effect on your vehicles cooling system. These systems shouldn't be topped up with water but rather with the correct coolant as approved by the vehicle manufacturer. It is a good idea to buy a bottle of the correct coolant and keep it in your garage at home for if and when your vehicle’s cooling system needs topping up.

If your car is fitted with a dipstick for checking the oil level, the engine needs to be warm but needs to have been stationary for 10 minutes before doing so. On many modern cars the oil level is checked by the on board computer, which will alert you if the level is low via a warning on the dashboard. If the oil level requires topping up, it is vitally important that you add the same oil with which your engine was filled at its last service and very often this will not be available on the garage forecourt.

Fluids like those for the clutch and brakes are hydroscopic, which means that they absorb water over time. For these systems to work optimally these fluids should be replaced completely every two or three years.

The clutch and brake fluids as well as the transmission fluid are best only checked and replaced by a professional, so ask your technician to do so when you book your vehicle in for it’s next service. These checks are not always part of the regular servicing schedule, but it is worth asking for them to be done.