Can I fill my car's windscreen washer reservoir with water mixed with dishwashing or other household detergent?
Your best bet to clean the windscreen is driving during a heavy downpour.
However, there are those sunny mornings when you get in your car and have to look out through a glass spotted with bird droppings. Usually they are stuck like glue and even several sweeps of your wiper with the washer continuously spraying will not remove them.
If you have access to water, then the surest way to get your windscreen clean is with a cloth and copious amounts of water. Most contaminants, including bird droppings, need to be soaked in water or windscreen cleaning fluid before they start to break away.
Good windscreen washing additives are available from most petrol stations and car accessories sections of supermarkets. They all contain some percentage of alcohol, so read the instructions on how much to mix with water.
Remember that when you use the water jets, some amount of the liquid eventually flows onto the car body. Hence, excessively strong washing solutions could streak your paintwork.
A windscreen washer reservoir containing any amount of household detergent must never be used. These liquids are formulated to remove grease and oils from ceramics, stainless steel and glass. Most of these are therefore detrimental to wax and even the top clear coating of body paint.