How to check you car's coolant levels

Protect your engine from overheating with a simple coolant check.

Checking your car’s coolant level regularly can help you spot potential problems early, reduce the risk of breakdowns and keep your vehicle running reliably on Australian roads.

• Help prevent costly engine damage by checking your coolant level regularly.
• Make coolant checks part of your routine when refuelling or before a long drive, especially in hot weather.
• Never remove the radiator or coolant reservoir cap while the engine is hot. Pressurised coolant can cause serious burns.

What is engine coolant, and why is it important?

Engine coolant is a specially formulated liquid that circulates through your car’s cooling system to regulate engine temperature. It typically contains a mixture of water and additives, including antifreeze and corrosion inhibitors, to help prevent overheating, freezing and internal corrosion.

Coolant comes in different colours, including green, red, pink, orange and blue. However, colour alone does not identify the correct coolant for your car. Different vehicles require specific coolant formulations, so always check your owner’s manual before buying or adding coolant.

Checking your coolant level is particularly important in Australia, where high summer temperatures, heavy traffic and long-distance driving can put additional demands on your engine’s cooling system. A low coolant level may indicate a leak or another mechanical problem that needs attention.

How to check your car’s coolant level

Checking your engine coolant is straightforward for most vehicles. Follow these steps to inspect the level safely.

1. Park your car and let the engine cool: Park on level ground, switch off the engine, apply the parking brake and allow the engine to cool completely before opening the bonnet or inspecting the cooling system.
   
   Never remove the radiator cap or coolant reservoir cap while the engine is hot. The cooling system can remain pressurised after driving, and escaping steam or hot coolant can cause serious burns. Cooling times vary, so allow several hours if necessary and follow your vehicle manufacturer’s instructions.
2. Locate the coolant reservoir: Open the bonnet and secure it using the bonnet support or strut, as applicable. Find the engine coolant reservoir, which is usually a translucent plastic tank connected to the cooling system. It may have a coloured cap or a coolant warning symbol.
   
   If you’re unsure where to look, consult your owner’s manual. Some vehicles have different reservoir layouts, and certain designs require specific checking procedures.
   
   
3. Check the coolant level: Look at the markings on the side of the reservoir, usually labelled MIN and MAX, or LOW and FULL.
   
   When the engine is cold, the coolant should generally sit between the minimum and maximum marks, ideally at the manufacturer’s specified cold-fill level.
   
   If the coolant is below the minimum mark, you may need to top it up. If the reservoir is empty, or the level keeps dropping, arrange a professional inspection rather than repeatedly adding coolant.
4. Top up with the correct coolant if needed: Check your owner’s manual for the correct coolant specification and follow the manufacturer's instructions for topping up. Use the specified premixed coolant or the recommended concentrate and water mixture, as appropriate.
   
   For most modern vehicles, coolant should be added to the designated reservoir rather than directly to the radiator. Never assume that a coolant is suitable simply because it has the same colour as the liquid already in your car.
   
   Avoid overfilling the reservoir, and make sure the cap is securely refitted. If you’re unsure about the correct product or procedure, ask a qualified mechanic for help. 

What should you do if your car keeps losing coolant?

Coolant levels should not continually drop under normal operating conditions. If you regularly need to top up your coolant, there could be a leak or a fault in the cooling system.

Look for signs such as:

• Puddles or coloured fluid beneath your parked car.
• Visible leaks around hoses or the coolant reservoir.
• A persistent sweet smell around the vehicle.
• An engine temperature warning light or a temperature gauge reading higher than normal.
• Steam coming from beneath the bonnet.

If your car begins to overheat while driving, pull over somewhere safe as soon as possible and switch off the engine. Do not continue driving with an overheating engine, and never open the cooling system while it is hot. Allow the vehicle to cool fully and arrange roadside assistance or a mechanic’s inspection if needed. 

Keep your car road-ready with My NRMA Rewards

Regular vehicle checks can help you identify potential issues before they become bigger problems. Checking your coolant is a useful addition to your routine maintenance, particularly before a road trip or during periods of hot Australian weather.

My NRMA Rewards Members can also access discounts at Repco which may help save on eligible car care products and supplies. Check the current offers and product compatibility before purchasing coolant.

A few minutes spent checking your coolant could help protect your engine, reduce the risk of an unexpected breakdown and keep you moving with confidence.