Take care when it comes to coolant

Different types don’t mix well together, so it’s best to check what your vehicle needs

Not that many years ago, if your vehicle needed coolant for a top up, it was a relatively easy and painless affair. You’d simply drop into your favourite parts store, grab a jug off the shelf, add the required amount directly to the radiator (once the engine cooled off, of course) and you’d drive off safely — and coolly — into the sunset.

Sadly it’s not quite that easy anymore. Now there are three distinct types of coolants, and mixing them can lead to expensive troubles. They all still do the same things: stay in liquid form at extremely low temperatures, resist boiling at higher temps, lubricate moving parts and resist corrosion. But while traditional ethylene-glycol coolant is still green in colour, the other two varieties — OAT (organic acid technology) and HOAT (hybridOAT) — range in hue from pinkish orange to reddish purple.

Mixing green with any others can cause chemical reactions, leading to sludge buildups that can restrict coolant flow and that may overheat the engine. Older engines that still use a lot of brass in radiator and heater-core construction benefit from green coolant, whereas newer vehicles with ample aluminum parts need the corrosion protection found in OAT or HOAT blends. And making a choice based solely on colour won’t necessarily lead to the right result.

The most common mistake when it comes to adding engine coolant is topping up when it isn’t necessary. Most vehicles use coolant recovery bottles that have minimum and maximum level lines, and coolant should only be added if the bottle is empty. If only a litre or so is needed, you can often add distilled water to mix with the coolant when the engine is running. Almost all automakers provide more than enough freeze protection in their formulae to withstand a little water without risking a freeze-up.

However, never add water to a coolant bottle when the vehicle is parked outside in sub-zero temps or even attempt to drive immediately after this when it’s cold. It takes time for the water to mix with the engine’s coolant to achieve freeze protection.

Also, before you pop the cap on any recovery bottle, make sure it isn’t a pressurized type. Those bottles will have a sturdy cap unlike the simple pop tops on non-pressurized bottles. If yours is pressurized, make sure the engine is completely cooled off to avoid a hot antifreeze eruption.

If your ride does need coolant, refer to the owner’s manual to get the right type. Universal coolants that claim to be good for any engine aren’t recommended. Read the container’s label to find out if it’s pure or premixed; pure coolant may actually freeze as fast as water and these products require a 50/50 dilution with water to be effective.

Be careful when storing coolant when pets and children are around because coolant has a particularly sweet smell and taste but can be lethal to smaller creatures.