The Right Way To Top UP Fluids in Your Car

There are many engine components that require fluid of one type or another. Over the next few pages, we describe how simple it is to check the fluid levels and top up if necessary.


√ DO check the fluid levels, for every engine system that requires fluid, at least once a month – especially before setting out on a long journey.

⊗ DON’T check fluid levels when your car is on a slope – you will get a false reading.

√ DO remember to replace the cap every time you fill up or check the levels. You don’t want fluid evaporating or leaking out all over the engine.

Engine oil

Oil lubricates the moving parts within an engine, prevents corrosion and helps to keep the engine cool. If the oil level drops too low, an engine will quickly wear internally and serious damage could result.

It is a good idea to check the oil level periodically, especially before a long journey. With the engine cold and the vehicle on a level surface, locate the engine oil dipstick [A] and remove it. Wipe it clean, replace it and remove it once again, checking that the oil level is between the upper and lower level markings [B]. Add new oil at the filler cap if required, wait a minute or so for the new oil to drain to the sump at the bottom of the engine and repeat the procedure with the dipstick until the oil level is at the upper mark.

After time, the oil becomes dirty and loses some of its lubricating ability. While adding fresh oil will help, an oil and filter change is recommended at least every 6,000 miles by most manufacturers.

Add oil gradually, constantly re-checking the level once it has drained through

Add oil gradually, constantly re-checking the level once it has drained through

Add oil gradually, constantly re-checking the level once it has drained through.


The fourth most common cause of breakdowns is overheating, something the coolant is supposed to prevent. Usually the reason for overheating is not the coolant itself, but an associated problem, such as a holed radiator, stuck thermostat, failed water pump, an electric fan that has ceased working or a coolant leak. Occasional topping up with coolant is normal, but if it’s a frequent occurrence there is often a leak somewhere. If you cannot spot one at the front of the car, either from the radiator, engine or a hose, check the exhaust. If water persistently drips from the tail pipe, or white smoke doesn’t clear, the head gasket may have failed. A trip to a garage will be imminent if this is the case!

The Right Way To Top UP Fluids in Your Car

As well as preventing the water from freezing in winter, anti-freeze in the coolant helps the engine to run cooler. Check the coolant level frequently, and in winter add the recommended amount of anti-freeze [A]. As with oil, check the coolant level before long journeys. The coolant reservoir [B] will have minimum and maximum levels. Fill the reservoir to the ‘maximum’ level with the maker’s recommended water/anti-freeze mix. If you drive an older car, it may not have a coolant reservoir, in which case the coolant is added directly into the top radiator tank.

Fill the coolant reservoir to the ‘maximum’ level marker with a wateranti-freeze mix. 

Fill the coolant reservoir to the ‘maximum’ level marker with a wateranti-freeze mix.

Power assisted steering

Many, though not all, cars have power assisted steering these days. You may not realise there is a problem with this until you hear a hissing noise as you turn the steering wheel or if the steering becomes notchy or juddery. With luck this will just indicate that the power steering fluid level is low. If this is not the case, then the power steering system may be damaged, leading to the steering becoming harder and harder to operate.

Different types of systems use different fluids, though most operate with automatic transmission fluid. To add fluid to the system or check the level, locate the fluid reservoir [A]. Some will have maximum and minimum level markings on the outside of an opaque reservoir, while others will have a dipstick inside the cap. Some reservoirs are part of the power steering pump, which transfers the fluid to the power steering system components. Add transmission fluid when needed and top up to the correct level [B], taking care not to overfill. This varies depending on the particular model, so follow the instructions given in the car’s manual.

The Right Way To Top UP Fluids in Your Car

More new cars now have electric power assisted steering (EPAS) systems, which use an electric motor to provide additional directional control. The EPAS system is gradually replacing the hydraulic steering system, as EPAS does not require engine power in order to operate.

Brake fluid and clutch fluid

The brakes are probably the most important components of a vehicle, but they won’t work without brake fluid. As the brake pads wear down the fluid level drops accordingly, but needing to regularly top up will indicate a leak somewhere. For example, if brake slave cylinders within the brake drum leak badly, you’ll notice brake fluid seeping from the bottom of the drum on the inside of the wheel. Brake pipes themselves can also leak fluid, or the brake master cylinder can leak either externally or, more difficult to spot, internally.

The Right Way To Top UP Fluids in Your Car

The brake fluid reservoir is most often found on the master cylinder, which is almost always mounted on the bulkhead between the engine and passenger compartments. Topping up the fluid is simply a matter of locating the reservoir [A], removing the cap and adding fluid[B] to the specified level, usually marked on the outside of the opaque reservoir [C].

The Right Way To Top UP Fluids in Your Car

Some cars have hydraulically operated clutches (your handbook will tell you if this is the case). If so, the clutch fluid reservoir will probably be located alongside the brake fluid reservoir. Locate and fill as necessary.

The Right Way To Top UP Fluids in Your Car

Manual and auto transmissions

The transmission of a vehicle, commonly referred to as a gearbox, is used to select a gear to suit engine speed either manually or automatically.

Whatever type of transmission your car has, it needs lubrication. In the case of an automatic, transmission fluid is a necessary part of the transmission’s function, so needs regular checking. Consult your car’s handbook for the exact location of the gearbox filler plug, as well as the type of transmission fluid to use.

The Right Way To Top UP Fluids in Your Car

To check the automatic transmission fluid level, the engine should first be warm, preferably after a short drive to pump fluid through the transmission. With the engine running and the gear selector in ‘park’ or ‘P’, locate the dipstick tube [A] and remove the dipstick. As with the engine oil dipstick, markings will indicate the upper and lower limits of fluid level [B]. Wipe clean and replace before removing again to check the level.

The Right Way To Top UP Fluids in Your Car

If topping up is required, most automatic transmission fluids are sold in bottles with plastic tubes extending from their caps, which makes filling through the dipstick tube easy. Recheck the level after topping up.

If your car has a manual gearbox, checking the oil will invariably mean accessing the underside of the car, which may be better left to a garage.


√ Always check your handbook to ensure you use the correct transmission fluid, as several types are available.

√ Manual gearbox oil is not the same as engine oil. Use only the type specified for your vehicle.

√ Ensure the vehicle is on level ground before checking the transmission fluid or oil level.

√ Some vehicles are equipped with gearboxes which are sealed, in which case the transmission fluid does not need checking.

 Windscreen and headlamp washers

You won’t appreciate how important windscreen washers are until you have a dirty windscreen. Remember, too, that your headlights will be just as dirty, cutting down on their effectiveness at night. Not all cars have headlamp washers, but if yours has, check and top up the fluid regularly with the specially formulated screenwash available for windscreen washers, which also prevents it from freezing during cold weather in winter.

Locate the windscreen wash reservoir under the bonnet of your car [A], remove the cap and fill to the required level [B] with screenwash. Remember to top up the reservoir for any rear screen washer your vehicle may be fitted with. This is often located in the boot, but refer to your manual.

The Right Way To Top UP Fluids in Your Car

If the reservoir is full and the washers still don’t appear to work, you may have a blocked washer jet. The jets can usually be cleared by inserting a pin into the nozzle [C]. Occasionally, in severe winters, the washer jets may freeze and it may take a while for the engine heat to thaw them. Avoid continually pressing the washer switch as you could damage the pump motor.

The Right Way To Top UP Fluids in Your Car

Topping up the battery

Car batteries come in various sizes and power outputs. A bigger engine will require a battery with a higher power output capacity. Modern cars are designed to take a specific sized battery for each model. There are also various types of battery, with most modern versions being maintenance free – a fit-and-forget-about-it battery!

Conventional batteries, however, require periodical checking to ensure the electrolyte – the fluid inside the battery – is at the specified level. These batteries have plastic plugs on their top surface, which are then removed to enable you to check the fluid level. Some of these plugs screw on, some twist on and some have to be prised off with a screwdriver or similar implement. It will be obvious to you which type is fitted when you come to remove them.

TIP: Batteries contain acid, which will spoil paint, corrode clothing and burn the skin. Handle with care!

Remove all the plugs [A] and visually check that the metal plates inside each cell are submerged in fluid. Some batteries have a level gauge inside the cell to help with this. If any cell is running low of fluid, top up with distilled water [B], which is available at any motor spares shop or garage. In emergencies, cold water from a boiled kettle will suffice.

Replace the plugs securely. If your battery is flat it will still require charging (Charging the battery), but topping up the fluid will ensure that it can now operate at full working capacity once it has been recharged.

The Right Way To Top UP Fluids in Your Car