Skoda YETI - 05-2010 Owner's Manual page 216

Caution

On no account should you add radiator antifreeze or other additives to the wind-
screen washer fluid.

If the vehicle is fitted with a headlight cleaning system, you should only add
cleaning products which do not attack the polycarbonate coating of the headlights to
the windscreen washer fluid. Please contact your specialist garage, who will tell you
which cleaning agent you can use.
Using the system Safety Driving Tips General Maintenance
Inspecting and replenishing
Breakdown assistance Technical Data
215