Apparently I’ve been misunderstanding the purpose and usage of Mercedes windshield washer fluid ever since I had the ‘C’ class.

It’s winter here in the Free State (that’s a prohibition reference…), and snow, sleet, and rain mixed with road salt means you can barely drive a mile without hitting the wiper blades and a washer squirt. So you use a lot of washer fluid this time of year. Best to stock up and maybe even carry some spare in the trunk.

When I bought the ‘C’ class back in October of 2007 I vowed to give it everything the factory said. This involved not just the usual factory specified servicings, but also using only Daimler approved things like Mercedes anti-freeze (its a weird blue color, I suppose just so you know it’s not the stuff you get at Manny, Moe and Jack’s). As it turns out, this extends to the wiper wash fluid. It’s like buying an Apple computer or smart phone: you aren’t just buying a product, you’re buying into a Culture, a complete Ecology. And it’s not just a specific Mercedes-Benz washer fluid you need to use…there are summer and winter mixes. I could swear I was told initially that they were additives you mixed in with the usual store bought blue washer fluid stuff.

After I’d bought the ‘C’ class I found out about the summer/winter washer stuff and asked the dealer for some. The guy behind the parts counter gave me one a little 40ml flask of “summer”, and told me to just mix it with a gallon of regular washer fluid. So from that moment on I assumed it was an additive you mixed with the usual store bought washer fluid. When winter came around I asked for the winter mix and apparently they just sold me summer flasks and told me it was winter…basically selling me me what they had in stock instead of what I asked for. Last year they even told me that the additive you got was now for both summer and winter.

This year (dealership has since changed hands…) I asked again for the “additive” and was told all they had was summer. I told the guy behind the parts department desk that I’d been told previously that summer and winter were now one and the same. He shrugged and said I could use it that way here in Maryland, but they’re different and if I wanted he could order me the winter stuff instead.

Well I’m a do it the right way kinda guy so I said sure go ahead please order me the winter stuff. How many, he asks. I did a quick mental calculation based on 40ml flasks and asked for six of them. Then I leave a little ticked off and thinking the previous parts guy was just selling me what he had instead of what I wanted and I’d got bamboozled. I got the call this morning that it came. Six 1 litre bottles.

WTF???? So I go home thinking now I have a lifetime supply of winter additive. The bottles are cheerfully international, with pages and pages of safety warnings in every language you can think of and I can’t make heads or tails of how much of this stuff I’m supposed to add to washer fluid. I’m trying to decode the pictogram instructions and they don’t make sense. It almost looks like…wait a minute…is this stuff concentrate instead of additive??

I do some Googling. Sure enough…it’s concentrate, not additive. You mix it with water to make a quantity of washer fluid. Those little 40ml flasks of the summer stuff are enough to make a gallon of summer temperature washer fluid. You mix the winter stuff with water according to a chart for how low you expect the temperatures to drop. I had no idea until just today.

I’ve been doing it wrong this entire time. Well it didn’t damage anything at least. A one litre bottle of winter solution concentrate will make me two liters of working solution that protects the system down to -4. It really never gets that cold here in Maryland so it should be good enough. There are less expensive products out there that claim to work better, and even de-ice better, but a Mercedes-Benz is just different enough from the usual that I’m really very reluctant to use anything but what the factory approves, even in the windshield wash. If that makes me a sucker so be it. I’m still in love with this car.