I have two bottles of MBZ Formel VR9422 Summerwash in 40ml size. The German to English translated instructions are somewhat confusing. Can you decipher this:

"Windshield-washer to be mixed with Winterwash only. 1 bottle + 4-5 liter of water."

Is this saying mix with another product called "winterwash" and/or water? Thank you.

Sounds like your talking about the windshiled washer fluid additive. If that is the case then the concentrate dumps into a mostly full washer reservoir and acts as a "booster".

Hope this helps...Lee