The Mercedes fluid was a concentrated soap, maybe 4 oz to be disolved in a gallon of (my) water at home in my container. The stuff you buy (typically blue) does have a high alcohol content to prevent freezing. With the water based solution my washer fluid sensor floats, so no warning light. With the blue, less dense alcohol based fluid it sinks and the light comes on. I took the sensor out and tested it with an ohm-meter in each fluid.
OK, now for the next obvious question,... does a new sensor change this condition (work with the alcohol solution). Anyone tried a new sensor?
(BTW- this is on an 87-300sdl)