Schumi,

Hmm.... here are the results of my experiments. I filled my washer tank with the "blue" alcohol based washer fluid. My low fluid light came on. So I took the sensor out of the tank. In a bucket of water I measured the continuity. Sure enough, in water the float in the sensor would rise and it would read correctly. In a bucket of alcohol based fluid, the float in the sensor would sink, turning the light on. So in my mind the sensor does not have the bouyancy to float in the alcohol.

To others... is this normal or a washer-logged old sensor? Would a new sensor allow the alcohol based solution to work?

I noticed MB does sell MB washer fluid mix for $3. It is a few ounce tube of goo that goes in a gallon of water. This works fine provided it is not below freezing.

I did talk with another MB owner that said his sensor was "gooped up". He cleaned his and now it works fine. (I didn't ask about what type of washer solution he uses).

Let me know what you find out.
Chuck