My understanding regarding methanol is that when small quantities are in the open (such as spread thinly on a surface and left to dry), it will rapidly evaporate from that surface due to a high vapor pressure. Is this also true for methanol mixed within substances such as windshield wiper fluid? Will the methanol evaporate from the wiper fluid residue on a surface or stay there indefinitely until washed off?
Generally, a substance in a solution will remain in that solution. Methanol will evaporate from the solution a little bit quicker than the water, but that would not be noticeable for quite some time. Spread in a thin film over a windshield you do see the effect of somewhat faster evaporation than you might see in a rainstorm.