How is the oil film on car glass formed?

[MalachiLee]

Car glass oil film may be formed due to automobile exhaust, oil smoke pollution, or residues from insects, bird droppings, resin, jam, etc. Automobile exhaust contains various pollutants produced by incomplete combustion. Frequent traffic congestion in urban roads inevitably leads to the adhesion of these pollutants on car glass, forming an oil film. Methods to deal with glass oil film include: using glass cleaner instead of tap water, as glass cleaner has better cleaning ability and provides lubrication and antifreeze functions that tap water cannot replace. Additionally, regularly applying a coating on the glass can prevent the formation of oil film. On coated glass, water droplets quickly slide off, ensuring clear visibility during rainy days.