Skip to main content
driving concerns

I read your story on windshield washer fluid and all the comments. I'm curious why manufacturers don't just add more alcohol, for bragging rights. "Good to -60 C" washer fluid would be a hit with the kind of consumers who think "more is better" and buy premium gas when their cars only need regular. Sure, it would be flammable, but so is the stuff we buy now. I'm also wondering why they use methanol here and not ethanol like they do in Europe?

– Jeremy, Whitehorse

I'm no marketing expert, but I doubt "now more flammable!" would spark sales for a product sitting in a plastic reservoir under your car's hood.

"If we added more methanol, there are laws we'd have to follow about labelling and packaging," says Angelo Macchia, product development manager with Recochem, a washer fluid manufacturer. "We'd have to put it in a metal can because it would be so flammable."

A quick washer fluid refresher: winter washer fluids in Canada are rated from –35 C to –49 C. They're a mix of water and alcohol. In North America, this is usually methyl alcohol, also called methanol.

General Motors spokesman George Saratlic explained in an e-mail that the freeze point roughly corresponds to the percentage of alcohol.

"A –35 C washer fluid will have not less than 38 per cent methanol," wrote Saratlic. "A 50 per cent methanol mixture freezes at –50 C."

Adding more antifreeze to the usual 35-40 per cent mix would mean less water and a lower freezing point. But too much methanol creates problems – it would require special packaging because it's flammable, it could damage your car's paint job and it could release more smog-causing volatile organic compounds (VOCs) into the atmosphere.

"Minus 49 is the practical limit," Macchia says. "And, making a product with a lower freeze point is not warranted."

A product good to –60 C might have been a big hit at the now-closed base in Snag, Yukon (which recorded the North American record low of –63 C in 1947) – but it's not necessary for Canadian drivers, Macchia says.

The fluid sold now won't freeze solid in the jug or in your vehicle's reservoir up to the rated temperature. But once it's out in the windshield, the methanol evaporates quickly, especially when you're travelling at highway speeds. The less methanol left, the faster the remaining water will freeze.

"It's not the same as the wind chill factor, which has to do with how cold it feels on skin," Macchia says. "But wind does make it cool faster – like when you blow on hot soup to cool it down."

So, even a flammable, paint-eating fluid rated to –60 C could freeze on your windshield if most of the methanol flashed off, leaving water (which freezes at 0 C).

"When we formulate it, we're measuring the freeze point of the liquid itself," Macchia says. "Freezing on the windshield doesn't happen that frequently – it's impossible to test for every possible road situation."

Freezing could happen if the fluid is diluted – by ice on the windshield or by water or summer washer fluid still in the reservoir.

Drain the reservoir before putting in winter washer fluid, Macchia says. If ice forms while you're driving, blast the defroster (which is meant to melt ice and frost) and flood the windshield with washer fluid until it melts.

"I'm not saying that because we sell the stuff," he says. "But you'll get more alcohol onto the windshield."

Other alcohols – like ethanol and ethylene glycol – do get added to some formulas, but most fluids are mainly methanol, water and colour. Some products also include water repellants.

Ethylene glycol turns to a gel at cold temperatures and would clog nozzles and make it tough to see out your windshield, Macchia says.

Methanol doesn't get viscous at low temperatures and it's not as corrosive as ethanol. Plus, it's a lot cheaper than the alternatives.

"Methanol is fundamentally the cheapest and most readily available," he says.

Send your automotive maintenance and repair questions to

Interact with The Globe