How to do fluid level checks

Fluid Level Checks Image

Checking the oil, coolant, screenwash, brake and clutch and power steering fluid levels on your car is a straightforward job that takes seconds to do. Some fluids should be checked once a week but others can go for longer before they need to be examined.

Some car models have sensors that warn you when certain fluids are low, via the dashboard, but it’s always worth looking under the bonnet (and under the car) to check the levels and for leaks.

This task requires no experience. You won’t need any tools - just some paper towels and maybe a funnel for topping up.

How long should your car’s fluids last?

With the advent of modern oils and additives, engine oil and coolant lasts longer than it ever has – but that doesn't mean you should ignore the service intervals.

It's generally recommended that you change your oil at least annually, or every 10k miles, whichever comes first. Although some manufacturers state shorter, or longer intervals between changes.

Coolant generally has a much longer service life, with some manufacturers recommending a 15-year, or 150k-mile change. Although a five-year or 50k-mile interval is a more common recommendation.

With engine oil and coolant, it's important that you consult your handbook, or Haynes manual to find out the correct intervals for your car.

 

How much does it cost to top up your fluid levels?

Only small quantities of engine oil or coolant are needed for topping up. And although it varies depending on the vehicle, a litre of oil or premixed coolant will normally cost less than £10.

Why you should check your fluid levels

Most of the fluids in your engine bay are critical for the car’s operation. Among the most important are the engine oil and coolant, which is why these should be checked weekly. A low engine oil level will cause the engine to wear more quickly, and if it drops to a dangerous level the engine could seize. A low coolant level could result in the engine overheating, which could cause severe engine damage too. Regular checking of the coolant level will alert you to a leak early, so any problem can be sorted before it leaves you stranded by the side of the road in a cloud of steam.

Brake, clutch and power steering fluid are still important fluids but don’t need to be checked as often. However, a drop in level from month to month could indicate a leak in the system, and it’s important to fix this as soon as possible, rather than to keep topping up the fluid. Bear in mind, however, that the brake fluid level drops as the brake pads wear, so don't be alarmed if it's not up the max-fill line.

When to check your car’s fluids

“Always make sure you use the correct fluids when topping up”

Weekly fluid checks include: engine oil, engine coolant and windscreen washer fluid (if possible).

Monthly fluid checks include: battery electrolyte (if the battery isn’t sealed), brake and clutch fluid.

Before carrying out any fluid checks make sure the car is parked on level ground. You’ll find it easier to do these checks in good daylight. Use your car’s handbook, which will show you where the fluid reservoirs are located. Always make sure you use the correct fluids when topping up - never mix different grades of engine oil and brake fluid. If in doubt, check in the Haynes manual or your car’s handbook.

Warning

Always make sure you use the correct fluids when topping up - never mix different grades of engine oil and brake fluid

How to check your fluid levels

Here's an example of how it's done

  1. Engine oil is checked with a dipstick. Remove it, wipe it clean, replace it, remove it again and make sure the level is in the correct zone
  2. Look for the engine coolant level on the side of the expansion tank. If it’s low, remove the lid only when the engine is cold
  3. You may not be able to see the screenwash fluid level if the tank is hidden from view, so simply pop the cap and top it up. Don’t use coolant antifreeze
  4. Brake, clutch and power steering fluid have separate reservoirs. Note that the brake fluid will drop over time as the brake pads wear - as long as it stays above the minimum level this is nothing to worry about

Checking engine oil levels

Your engine oil is the fluid you'll want to keep the closest eye on. Modern engines place great demands on their oil, so it is very important that the correct oil for your car is used.

If you have to add oil frequently, you should check whether you have any oil leaks. Place some clean paper under the car overnight, and check for stains in the morning. If there are no leaks, then the engine may be burning oil, or the oil may only be leaking when the engine is running.  

Always maintain the level between the upper and lower dipstick marks. If the level is too low, severe engine damage may occur. Oil seal failure may result if the engine is overfilled by adding too much oil. 

Before you start

  • Make sure that the car is on level ground. 
  • The oil level must be checked with the engine at normal operating temperature, however, wait at least 5 minutes after the engine has been switched off. 
 
Remember: if the oil is checked immediately after driving the vehicle, some of the oil will remain in the upper engine components, resulting in an inaccurate reading on the dipstick.  

Checking your engine oil is at the right level 

  1. The dipstick may be brightly coloured for easy identification. Withdraw the dipstick.
  2. Using a clean rag or paper towel remove all oil from the dipstick. Insert the clean dipstick into the tube as far as it will go, then withdraw it again.
  3. Note the level on the end of the dipstick, which should be between the upper (MAX) mark and lower (MIN) mark. Approximately 1.0 litre of oil will raise the level from the lower mark to the upper mark.
  4. Oil is added through the filler cap. Unscrew the cap and top-up the level. A funnel will help to reduce spillage. Add the oil slowly, checking the level on the dipstick frequently. Avoid overfilling.

Checking your coolant level

WARNING: DO NOT attempt to remove the expansion tank pressure cap when the engine is hot, as there is a risk of scalding. Do not leave open containers of coolant about, as it is poisonous.  

With a sealed-type cooling system, adding coolant should not be necessary on a regular basis. If frequent topping-up is required, it is likely there is a leak. Check the radiator, all hoses and joint faces for signs of staining or wetness, and rectify as necessary.  

It is important that antifreeze is used in the cooling system all year round, not just during the winter months. Don’t top-up with water alone because the antifreeze will become diluted.  

The coolant level varies with the temperature of the engine, and is visible through the expansion tank. When the engine is cold, the coolant level should be between the MAX and MIN marks on the front of the reservoir. When the engine is hot, the level may rise slightly above the MAX mark.

If topping-up is necessary, wait until the engine is cold. Slowly unscrew the expansion tank cap, to release any pressure present in the cooling system, and remove it.

Add a 50/50 mixture of water and antifreeze to the expansion tank until the coolant level is halfway between the level marks. Use only the specified antifreeze – make sure it is the same type and colour as that already in the system. Refit the cap and tighten it securely.

Checking brake and clutch fluid levels

Most cars with a manual transmission have a hydraulically operated clutch, which uses the same fluid as the braking system. 

Warning: hydraulic fluid can harm your eyes and damage painted surfaces, so use extreme caution when handling and pouring it. Wash away any spills with clean water immeadiately

Tools you will need

Checking your fluids is an easy job and you won’t require any tools. Most fluids can be checked by looking at the translucent side of the reservoir or via a built-in dipstick. For the latter you’ll need some rags to wipe the dipstick clean.

  • Rags
  • Funnel

How much do different fluids cost?

 

Engine oil £5-£25 per litre
Brake/clutch fluid £5-£20 per litre
Coolant £2-£5 per litre
Screenwash £1-£3 per litre
Power steering fluid £10 per litre
Gearbox fluid (not always possible to check) £5-£35 per litre
Garage fee savings £50-£100