i bought my '03 cobra used from the original owner and i noticed that the rain seems to sheet off like it was treated with a "rain-x type" treatment. i have used rain-x before and i didn't like it because it didn't last very long, and the results were worse than an untreated windshield between treatments. the son of the previous owner told me she didn't apply anything like this. i have had the car for two months and the rain still sheets off, so, did the factory apply anything like this and will i need to renew it and with what? TIA