I have been using Aquapel for many years on my vehicles. This is a great product!
Once I reach a speed of 35-40 mph in the rain, the rain starts to bead up and slide up and off the windshield. Using Aquapel I can either turn off my wipers or use them intermittently. This is extremely effective and dramatic at night times! Aquapel is unaffected by the wipers and frequent car washings. Aquapel lasts longer than any other product I have used. The application is still noticeable after six months for me. Living in the snow belt, I make it a priority to make sure I apply Aquapel to the windshield and rear windows for the winter months. Clearing snow and ice off my windows is amazingly easy as the snow and ice do not bond to the glass as untreated. I highly recommend Aquapel to all my friends!

You won't need them most of the time with this on your glass.
This is the best water repellant made, far superior to Rain X. Rain X works almost as well for the first day or two and diminishes very quickly after that and causes the wipers to smear.
It advertises good for 6 months but I find it can last for almost a year before I need to reapply it, but I only average 10- 15k miles a year on my vehicles. At highway speeds wipers aren't usually even needed in most rain situations, and with the way the rain beads up and rolls right off the vision through the windshield is greatly improved. I've been using this product for well over 10 years and 12 treatments for 37 from Tool Deals is about the best price I've found. It has a glass cylinder with the product inside that gets broken when you squeeze it so shelf life shouldn't be an issue, I try to buy larger packages of this to get the cost per unit down and have had some on the shelf for 3-4 years with no issues.

I can get all the glass done on my crew cab F350 or my wife's Expedition El with one applicator if I hustle and have all the glass clean and ready before I start, I always start with the windshield fist and by the time I'm and the rear windows the applicator is starting to get dry but it still helps.

Try it! you'll never want to be without it after using it.

I own a boat and for years I've suffered from rain stained windows--and then I discovered Aqrapel. Wow! Once applied your windows will remain stain free for at least six months. But a few words of caution. Make sure your windows are relatively clean and dry; secondly, apply the gel liberally on the window; and third , take the time to really work the gel on to the window, removing all streaks or haze. Then, get ready to be the envy of your friends. "How do you keep your windows so clean?"

Unlike RainX this stuff lasts, think of it as an epoxy rather than a wax. I was introduced to Aquapel when I was working at a high-end dealership where it was applied as part of the pre-delivery inspection by the detailers. Application is fairly straight forward, but you have to move fast. One applicator will do a windshield, but don't get greedy and try to do more. I usually do 2 applications the first year with a new car, then about once a year after that. If you wash your windshield whenever you get gas you won't really need to use your wipers and the less you use your wipers, the longer the applications last.

Aquapel is Awesome and It last a long time. I buy these 12 packs because I have 6 cars but it takes me more than two years because the applications last soooooooooo long if applied correctly and maintained correctly. What do I mean by Maintained? Well I live in Washington where they say it rains too much but with aquapel I DON'T use my wipers except maybe in parking lots or driving under 25 MPH so I don't wear it off prematurely. At gas stations I clean my glass and polish once in a while with a dry gas station towel. I wash the car maybe 8-12 times a year and dry off the water so there are no hard water spots. I use Rain X washer fluid to clean a dirty windshield while driving. I may put on a coat of Rain X every six months on the cars I drive daily. With this maintenance, I have to reapply Aquapel every 1.5 -2 years! I really love and recommend this product! It saves wiper blades as well! Good Luck. Cheers.