A faint rainbow sheen at the windshield steadily indicates oily movie; a devoted glass cleanser or alcohol blend eliminates it
https://delta-wiki.win/index.php/How_to_Protect_Your_Windshield_from_Hail_Damage
A faint rainbow sheen on the windshield aas a rule shows oily movie; a committed glass cleanser or alcohol combination eliminates it nicely.