By Chad de Alva

In issue 45 of Upshift Online (May 2020)I wrote an article on motorcycle maintenance where I recommended replacing your bike’s coolant.  I am sure that a number of folks who read that article had a reaction to the effect of “If it isn’t broken, why fix it?”  So in this piece, I wanted to take a deeper dive in order to explain what exactly coolant is, how it works, and how to get the most out of it.  In our modern world where anyone can post anything to the internet, I want to make it clear that all of the information presented in this article was provided from leaders at several popular motorcycle-specific coolant manufacturers.  Now, with our sources cited, let’s get into all things coolant.

Coolant is a product that is designed to provide thermal protection to your motor by pulling heat from your motor and transferring it to the atmosphere through your bike’s radiators.  The heat your motor makes can only be effectively transferred while the coolant is in a liquid state of matter, so a good coolant must resist boiling into a gas or freezing into a solid.  Water is the workhorse ingredient of coolant, but water likes to freeze at 32 degrees Fahrenheit, and boil at 212 degrees Fahrenheit (at one atmosphere of pressure), so other chemicals need to be mixed with water to expand the temperature range in which the coolant stays in liquid form. 

These other chemicals also affect the water’s ability to conduct heat, which directly impacts how well the coolant can pull heat from your motor.  By using ethylene glycol or propylene glycol, a secret sauce of other additives, and ultra-pure water, coolant manufacturers strive to produce a product that will stay in liquid form, pull as much heat as possible from your motor, and conduct that heat to the bikes radiators as efficiently as possible.

Companies that make a quality motorcycle-specific coolant approach their formulation differently.  Motorex makes Coolant M3.0, which is an ethylene glycol coolant that is developed in partnership with KTM.  M 3.0 is what orange bikes come filled with from the factory, and KTM builds their service schedule around Motorex products.  Maxima makes a couple of coolant products: Coolanol, which is an ethylene glycol-based coolant, and Cool-Aide, which is a glycol-free coolant that is designed to work in racing applications where freeze protection is not required.  Engine Ice is yet another quality coolant that uses propylene glycol, which gives Engine Ice a few unique properties. Propylene glycol is less toxic than ethylene glycol, but it’s still important to handle and dispose of Engine Ice and all coolants properly.  It’s also important to check with any tracks or race sanctioning bodies for approved coolants – many places do not allow glycol-based coolants.  Although glycol is only one ingredient in the coolant formulation, other additives and even the purity of water used all impact how well a given coolant works.

While the additive packages that coolant manufacturers use are top secret, all of the coolant manufacturers I spoke with made mention of using very pure water in their formulations.  Even water that’s been purified by reverse osmosis can still have impurities like iron, lime, calcium, chlorine, and fluoride, that can all have adverse impacts on a cooling system.  So coolant manufacturers use de-ionized water to keep these unwanted minerals and chemicals out of their coolants.  This is also the reason that all of these coolant companies sell ready to use coolant which is pre-mixed with this de-ionized water at the factory – it makes the products easy to use (no mixing at home), and helps ensure performance. 

Using tap water, bottled water, or water from your hydration reservoir to top off a bike that’s boiled over will introduce impurities to your cooling system which can lead to all kinds of problems down the road.  Adding water to pre-mixed coolant will also dilute the glycol and additives present in the system, which can further impact cooling system performance.  That being said, if you have to add water in the field to get home, by all means do it – just know that the best course of action is going to be a full cooling system flush to make sure you get all of the unwanted impurities out.  If you have to add water to your bike in the field, it’s probably a good call to figure out why your bike overheated in the first place.  Are you riding in extreme conditions, like a super muddy track where you’ve completely blocked off airflow to your radiators with mud?  Do you need to add a fan, adjust your fueling, or do you have some other issue impacting your cooling system’s performance? 

Using quality motorcycle-specific coolant also matters.  Yeah, you can buy a gallon of big box store coolant for the price of one liter of quality motorcycle coolant, but you are rolling the dice just to save a few bucks.  Modern motorcycles are high performance machines that are exhaustively engineered – their cooling systems only have a liter and change worth of capacity, so every drop of coolant counts.  The coolant you can find at your local big box store is most likely formulated to work in more generic applications like a John Deere tractor or an old cast iron V8.  Both of which are much lower performance motors with significantly higher capacity (gallons, not liters) cooling systems where every drop isn’t as critical.  Using the cheap stuff may work, but if it leads to corrosion, clogging some part of your cooling system, or worse case, cooking your motor, was it worth it to save ten bucks?

To get the best possible results out of a quality motorcycle coolant, here are a few practices to follow:  Change your coolant annually, more frequently if you are racing or regularly riding in extreme conditions.  Nothing lasts forever, and just like fork oil and engine oil wear out, so too does your coolant.  When you go to replace your coolant, pay attention to what is coming out the drain – if anything besides coolant comes out (sediment, sludge, etc.), further cleaning and/or flushing is required.  If you are switching from an ethylene coolant to a propylene coolant – follow the directions.  You need to get all the old coolant out for best results.   If you are not sure of what flavor of coolant to use, pick a premixed coolant from a quality manufacturer – I’ve enjoyed trouble free performance out of all the products mentioned in this article. 

If your bike is overheating regularly, you may have other issues that could be impacting your bike’s ability to cool itself.  Remember, your bike is a system, and a change in one area could have a negative impact in another area.  Trading the stock exhaust for a free-flowing race exhaust and fancy intake without changing your fueling could be causing much higher combustion temps, which could be overwhelming the design limits of your factory cooling system.  On the other side of the coin, if you’ve smashed and straightened your radiators countless times, you may have reduced how well coolant can flow through your bike’s radiators, which means reduced cooling performance.  Radiators are designed to work with constant airflow, so if you’re doing a ton of soft enduro where you’re just riding in the rocks and not covering much ground, you may overheat without a fan to bring additional airflow to your radiators.  So before you blame a coolant for failing to perform, make sure that you’re giving it a fair shot with a bike that doesn’t have other underlying issues.

Motorcycles are amazing machines, and the performance that you can purchase off the dealer’s floor in perfectly stock form is very impressive.  Yet to be able to enjoy that level of performance ride after ride, year after year, you have to take care of your bike.  That means proactively replacing fluids like coolant.  For some reason, coolant is one of those things where riders will just leave it until it fails, and then get angry at their bike for letting them down when it overheats.  We are religious (hopefully) about changing our engine oil on the specified interval, so why doesn’t everyone do the same with coolant? 

“If it ain’t broke, don’t fix it” does not apply to motorcycles.  If it’s been a year or more since you changed your coolant, add some to your shopping cart next time you place a parts order.  As long as your cooling system is in good health, literally all you need to do is swap your old coolant out with one of the quality brands that are mentioned here.  Preventative maintenance goes a long way to keep your bike happy, and if you take care of your bike and keep it happy, it will continue to perform, which will make you happy.  Now, go change your coolant and get out and ride!