Radiator Coolant Basic Maintenance


Bryan Bosch

There are tons of threads on ThumperTalk about oil changes, but far fewer on radiator fluid. Because of this, I thought that this would be a good topic to cover.

At a minimum, radiator fluid should be changed once per year. If you race, at least twice a year. When you do this, it's a good idea to flush the system with white vinegar and distilled water (50/50 ratio).

After you've drained the old coolant, fill it up with the vinegar/water solution, run your engine until warm. Drop the solution and fill with clean water to flush the system. Drain the water and fill to the correct level with your favorite coolant. Do not overfill.

The acid in the vinegar does a good job of cleaning out the old coolant and contaminants but will not harm engine seals.

In terms of coolant, there are lots of choices and you can't go wrong using what your manual recommends. Most coolants are ethylene glycol based, so make sure to dispose of it where your pets (and young kids) aren't exposed to it. Because it's sweet smelling and tasting to them, they'll drink it and if they ingest enough, dead puppy or kitty.

I personally use Engine Ice. It's propylene glycol based, making it much less toxic to humans, animals plants, etc... and it's premixed with distilled water, ready to run with freeze protection down to -26 and a boiling point of +256.

If you live where winters are cold and you choose not use a premixed coolant/antifreeze, be sure to check the mixture with a hydrometer. You can get them for cheap at just about any auto parts store. You simply suck up some fluid, count how many balls float and cross reference the number of the freeze protection chart.

Also, the specific gravity of ethylene glycol and propylene glycol are not the same, so make sure that you use the correct hydrometer. For example, Engine Ice claims freeze protection to -26, but an ethylene glycol specific hydrometer will read only to +20. Not a problem per se in this example (you'd still be well protected), but the other way around could be trouble. I've found that some hydrometers just don't specifically say what coolant they are for. However, most are for the more traditional ethylene glycol.

Hopefully this is of value to some and I've always had excellent results following these practices. May winter come late and that you log lots of happy, trouble-free miles.




User Feedback


I ersnally think 1 time a year is overkill, let be a little environmentallly responsible, same as in oil changes!

But that said. let your conscious be ur guide!

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On adding water to the vinigor and the water flush. There are debates on the effects of the cl2 in water (chlorine). I make chlorine for the past 23 years and can tell you that chlorine is some bad stuff. It can eat carbon steal and stainless steal like there nothing to it. Even at the right temp start a chlorine and metal and not stop till one of the other burns up. But there is very little in tap water, is it enough to do harm? With the anti corrosion in anti freeze I would guess if you ever see corrosion in a radiator it is from tap water. I usually drain my stock fluid at some point flush with di water and refill with engine ice and have had radiators over 5 years old and the flues right below the cap look like new. Anyway just research tap water in radiators and you decide for yourself. We had large chill water systems that we only used mill water (well water) plus anti freeze and did not use di water because the engineers says that di water does not react and cool the metal surfaces right but every time we open that system it is caked with rust.

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Great article. Also a good idea, is to change out the factory fill after your first few hours on a new bike. They always have metal contamination.

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