It's freezing cold in Canada and I suspect the weather or time has caused a leak in my washer fluid reservoir. I would fill up and within a day or so, my warning light comes on indicating the fluid level is low. I wouldn't even use it too much.

A couple of questions:

1) should i worry about it leaking? Can the fluid safely drain through the engine bay?
2) can this be fixed by DIY?
3) anyone have instructions or experience with this?

thanks in advance.

If no one gets back to this thread with a procedure, I'll pop the hood on our 2013 and see if I can't shine some light on your question.

Before you go and buy a new tank, you should first find the source of the leak. Tank may not be the culprit.

I suspect the grommet on the washer fluid pump is leaking. Obviously, I am guessing [the source of the leak] without even looking at the car or leak. Based on my limited experience, I have seen that grommet leaking on several Merc and BMW cars. You can confirm the source of the leak by shining flash light on the washer pump where it attaches to the tank.

On other Merc and BMW vehicles, I removed the front left (drivers side in US) wheel, then peeled the front portion of the wheel liner. You will see the washer fluid tank. You will see washer pump. On some vehicles, there are 2 pumps (one for headlight washers and the other for windshield washers and rears). Cost of that grommet shouldn't me more than few dollars. That grommet comes with the strainer (to filter dust particles in the water). Put a pail or something under the tank to catch the washer fluid. Pull up the pump straight up (use screw driver as leverage, if necessary). Remove the grommet and install new one (just insert the grommet on to the stem of the pump and insert the grommet plus the pump in to the receiving hole in the tank. Fill up the tank. Check for leaks, button-up the wheel liner. Install the wheel.

You really don't need to remove the wheel, you just need to turn the wheel all the way inside (towards right). Removing the wheel makes the job easier, especially if you are doing this first time.

Above picture is from my BMW (530i). Arrow is pointing to the grommet I was referring to. Shape of the tank and specific location of the pump may vary but the concept is the same on these vehicles. I will see if I have a picture from my MB C280.

This is correct, but to make a fix (google for $5 rubber nipple set from princess auto) on w166 require to take off wheel cover.

Overwise, replacing water tank is very costly as it comes in one assemble including water line with heating and cost $$$

Those nozzles may be for the headlight washers (if your car is equipped with headlight washers).
Red fluid? May be grit/particles turned that stuck fluid [in those nozzles] in to red color due to not using those washers for a long time. Just a guess...

Transmission fluid sharing the same tank as windshield washer fluid? ___NO___
Whoever told you that, I'd stay away from that person. :-)