Roads Overview

Beat the Heat - Our Top Tips for Summer Driving

With warmer weather upon us here in Australia, we thought we would share our top tips for ensuring that your vehicle is ready for the summer.  We look at some simple cooling system maintenance checks, as well as some other general tips and FAQs, to help you prepare for your summer drives and to reduce the risk of your engine overheating.


To start with the obvious, your engine coolant plays a vital role in maintaining the health of your car, especially in warmer weather.  Making sure your car has enough good quality engine coolant in the system is critical.  Running low coolant levels can expose your engine to overheating, which may lead to internal damage and costly repairs.

How do I check the coolant level?

As each make and model of vehicle is different, refer to the owner’s manual for the location of the coolant reservoir and the checking procedure.  Before you check your coolant level, you must ensure that the engine is off and has cooled down.  NEVER open the cooling system if the engine is hot, as this may cause injury.  Locate the coolant reservoir and check to see if the coolant level is sitting between the ‘minimum’ and ‘maximum’ markers.  Depending on your vehicle, you may also check the fluid level in the radiator by carefully opening the radiator cap – put a towel or a thick cloth on the cap before removing it, as the cap is under pressure.  Release the pressure, and then remove the cap completely.  Again, it is very important that you do not remove the radiator cap while system is hot.  The fluid in the radiator should be at the top of the radiator.


If the coolant levels in the reservoir and/or radiator are low, you will need to top up the coolant using the recommended coolant for your vehicle that is already in the system, mixed to the correct concentration using demineralised or good quality water.  If the fluid level in the coolant reservoir is low, top it up by adding the premixed coolant to the correct level.  If the fluid level in the radiator is low, add enough premixed coolant so that the fluid sits just near the top of the radiator.  If any coolant is spilt on paintwork, flush off immediately with clean water.

Can I just add tap water?

Topping up a system with plain water will dilute the coolant – doing this will weaken the protection provided by the additives in the engine coolant.  Further, ordinary tap water often contains appreciable amounts of dissolved minerals and particulates which can lead to scale formation that will impede the efficient functioning of the cooling system and may cause system failure.  Properly formulated engine coolants, including water based coolants, contain corrosion inhibitors and water pump lubricants that are critical to maintaining the health and efficiency of an engine.  Coolant should always be topped up with the correct concentration of the existing coolant in the engine.  You may need to make up extra coolant if using a concentrated coolant in order to use as a top up solution in the future.

If in an emergency, you may use good quality tap water to top up the system as a stop-gap solution until the correct coolant is available.  However, you must add the correct coolant as soon as possible to prevent engine corrosion and to ensure your cooling system is functioning effectively.  Once the correct coolant has been added, you can test the concentration of the coolant in the system using test strips such as PrixMax Coolant Test Strips to ensure that the concentration levels in the system are correct.

Can I mix coolants?

We do not recommend mixing coolants.  This is because it can be difficult to know what coolant is in the engine, whether it has exceeded its service life, and whether it contains depleted inhibitors or other contaminants.  Some additive technologies in coolants are not compatible with others, and mixing them may not only compromise performance but may also cause damage to the cooling system.  If you’re unsure, the best course of action is to flush out the system and fill with the appropriate coolant. 

What if my coolant levels are always low?

If you find that the coolant level has dropped significantly or requires regular topping up, it may mean there is an issue with the cooling system, such as a leak.  In this case, we suggest taking the car into your dealer or repair shop to give it a check-up as soon as possible.


Inspect the engine for signs of coolant leaks.  The particular areas to check are around the hoses and hose clamps, the thermostat housing, and the water pump.  Inspect the hoses for cracks and replace any hoses that feel hard and brittle or exhibit surface cracking. 


Externally check the radiator core for insects and other blockages and clean them out by hosing down.  Don’t attempt to brush the core, as the cooling fins are fragile and can get damaged.


Most modern passenger cars have an electric cooling fan (some have more than one).  The fan is designed to come on when the temperature of the coolant rises to a certain temperature.  You can check whether the fan is working by turning on the air-conditioning in your car.  Then, with the engine running, open the hood and listen for the cooling fan. If the fan isn’t running, it's not working and you will need to have it fixed.


Regularly check the temperature gauge while driving.  Overheating can ruin an engine.  If the engine is actually overheating — that is, the indicator is near, or in, the ‘red‘ zone, or the temperature light comes on — pull over as soon as possible (or when safe to) as you will risk damaging the engine.  If you can’t find the problem, let the engine cool down completely, check the coolant level and either have the car checked at the nearest service station or call for assistance.


The coolant in my system looks rusty / there is sludge in my radiator – what do I do?

The presence of sludge in the cooling system or rust and other contaminants in the engine coolant is harmful to your system, and may indicate that coolants have been incorrectly mixed in the system or a poor quality engine coolant has been used.  In this case, you will need to completely drain and flush the cooling system with PrixMax Radiator Flush or equivalent according to the product instructions, and fill with a good quality coolant that is appropriate for your make/model.  Refer to the owner’s manual for cooling system capacity, coolant requirements and filling procedure.

Over the summer, can I just use plain water in my engine?

No.  Using formulated engine coolants in your engine is vital at all times.  Properly formulated engine coolants contain corrosion inhibitors and water pump lubricants that are critical to your engine life.  During summer and in warmer climates, however, it is unlikely that the coolant will need to provide protection against sub zero temperatures and accordingly an “antifreeze” or glycol-based coolant may not be needed.  Where freeze protection is not required, advanced technology water based engine coolants, such as PrixMax RCP Platinum, are in fact far more effective at removing heat from an engine than glycol-based coolants due to the unparalleled thermal properties of water.

What other checks can I perform to prepare my vehicle for summer?

1.  Make sure your air-con is working efficiently.  If in doubt, have it checked by a qualified professional.

2.  Check the air pressure of your tyres, and if required, refer to your owner’s manual to check the maximum pressure, which must not be exceeded.  Look at your tyres – wear indicator bars can be found in the tread, the location of which can be indicated by a small arrow printed on the side wall of the tyre.  If the tyre is worn even with the wear bar, you must replace the tyres.  Check the tyres for bulges or other signs of damage, a local tyre shop can advise if the tyre should be replaced.  Finally, make sure you have a spare tyre that is in good condition and is inflated to the correct pressure.

3.  Check your engine oil, transmission fluid, brake fluid and power steering fluid.  Refer to the owner’s manual to top them up or replace them with the correct and recommended fluid types and specifications.

4.  Check the battery terminals for signs of corrosion (a light ashy coloured powder build up on the terminals) and ensure they are tight and clean.  A loose connection may cause damage to the electrical system and the battery and may contribute to break downs.  If the battery is older than three years, it’s worth having it checked out by a professional to ensure it is still in serviceable condition.