windscreen washer fluid and washer/wiper action

Why would the 2018 Owner manual SPECIFICALLY say not to use distilled water with the washer fluid? It says use clean clear water. Well you can't get any clearer or cleaner water than distilled, and as a chemist this beats me. Is a certain level of electrolytes required?
Thinking about this some more, our house receives beautifully clear water as it is filtered at the State reservoir, BUT it is known to be very "hard" as it has an high Ca++ level and drops left to dry on the car paint stand out. Therefore I would not think of using it in the washer bottle. Fortunately we have a rainwater tank and that is "soft" and I throw it over the car after hose washing with the mains water. The brake discs rust before my eyes if I forget to throw rainwater on them.

Also
When using the windscreen washer system (pulling the lever), do your wiper blades grind across the dry screen once before the fluid gets to the glass? Someone on another forum said the headlight washers work before the wipers but our car does not have washers. Someone else said the spray happens before the wipers start.

Has anyone a workshop manual to show what is what?

Golf "R" white, DSG, MY19 (build date Aug 2018), purchased Dec.2018.

I’ve noticed the wipers do one up cycle before any decent amount of water hits the windscreen. This annoys the hell out of me. In terms of water, I think I smell some clean spirit mixed in with my fluid, stock from the dealer. Maybe metho?

MY19 R Special Edition

I wont use adelaide water , rubbish , like you the tank is best .
Yes my headlight washer comes on first , always get a spray on windsceen before first wipe , but only just .

Quote:

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Originally Posted by notaGolfR

Why would the 2018 Owner manual SPECIFICALLY say not to use distilled water with the washer fluid?

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I wonder this too, I've always been told town water can contain minerals that build up and block the jets. I've always used Bosch wiper fluid mixed with distilled water. Haven't had the Golf long enough to have topped my fluid up yet.

The only thing I can think of is the way distilled water can snap boil, but surely that isn't the reason here...

hmm....... all very good suggestions, but I wonder (total guess) if the prohibition relates to the fact that distilled water is not electrically conductive. This means (I guess) that if the fluid sensor depends on the flow of a an electrical current through the water, it won't work if distilled water is used. Mineralised water is needed for conductivity to occur - as I said, just a hunch

Don

Ye know too much DV52. -.-

I reckon that's why.

Emailed my local Skoda dealer with VW part numbers, came back with


"We stock the Skoda washer fluid bottles that come in 250ml.

It also has a inbuilt dosage cap inbuilt as well.

They are $5.16 each"




Skoda RS230

Brilliant lot of replies thanks everyone. Yep... I reckon the electrolyte conductivity theory gets the gong. I like the way the fluid comes out on my screen as a spray rather than a jet but the wipers before spray is in the wrong order. Should be a simple improvement for VW to change along the way.
Elsewhere someone said the rain sensor launches the wipers too soon (before the screen is wet enough) and suggests turning the feature off. I betcha those wiper blades are pricey so I will doing what I can to prolong their life.

My car sprays before wiping, but only just. I hold the wiper in squirt position (from off/auto positions) ill hear the motor spinning for a second or so, and just as the water finally hits the windscreen, the wipers start to move. I suspect that if I just gave it a momentary pull-back and let go, the blades would move earlier.

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Originally Posted by Simonr23

My car sprays before wiping, but only just. I hold the wiper in squirt position (from off/auto positions) ill hear the motor spinning for a second or so, and just as the water finally hits the windscreen, the wipers start to move. I suspect that if I just gave it a momentary pull-back and let go, the blades would move earlier.

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You nailed it , i tried that and it happens , need to hold it down longer .