Purpose of alcohol evaporator is to collect moisture (water) caused by condensation in pressurized air system that then gets eliminated when the system is purged....... same alcohol evaporator is used in air brake systems for trucks. Try commercial truck depot where air-brake trucks are serviced to get authentic alcohol for the alc/anti-freeze reservoir.

Its called anti-freeze/alcohol reservoir in your Mercedes because alcohol evaporator prevents water/condensation from building up and then freezing in the system and causing lock up in colder climates this time of year........ a problem among commercial trucks in wintertime where air system is maintained at constant 110 lbs pressure and condensation produces a few ounces of water over several days of constant use. This advice comes to you from someone who has worked as over-the-road truck driver.