no, this isn’t exactly a pressing world issue–nor particularly interesting–but bear with me…
I recently bought a bottle of Rain-X and, despite applying it as directed, the results really aren’t that impressive.
Not only does the product wear off within a week–though the bottle says it should last at least a month–but rainwater doesn’t bead up all that well. Why do I use it? I like gimmicks.
Have you had better luck with the stuff?
yes, that should be “windshield,” not window.
What kind of car do you drive? What kind of condition is your windshield? I have noticed that it works best on sloping windshields like on my 91 mustang, and on my friends 72 chevy pickup it wont do anything. His has 28 years of waterspots on it, and is almost verticle.
Damn and I’ve been using it on my Windows 98 
I used to use it and loved it, I thought it worked great. However as you said it doesn’t last nearly as long as the bottle says and I got tired of reapplying it. Havent used it in several years. Hell, now I live in the freakin desert anyway so… Got any Dust-X??
I’ve used it successfully on an '88 Caravan and a '95 Caravan. It doesn’t last a month, but it lasts a lot longer than just a week, for me. How old/pitted was your windshield when you first used it? It if is already scored, it may not provide a smooth enough surface.
Do you run your wipers, anyway? I get the best results when I leave my wipers turned off until they are needed. Using them constantly wears of the glop.
Rain X always worked fine for me, and lasted a good long time to. Put alot on, and wipe into the glass until your arm falls off.
You can use rubbing alcohol too. It doesn’t last as long, but it’s much cheaper!
Rain-X worked just fine on my vehicles: 1996 Chevy S-10 and 1994 Oldsmobile Achieva. Worked better on the Olds due to the greater slant in the windshield. Didn’t even have to use the wipers except in heavy rain. Lasted a little less than a month on average. It really seems to depend on how much you use the wipers. However it was a pain to apply the stuff and it is somewhat expensive, which is why I don’t use it anymore.
How well does Rain-X compare to the newer built in rain beader upper things on some cars I’ve seen. I don’t remember exactly but the mirrors were coated or created w/ some titanium compound that’s supposed to do the same thing as Rain-X but technically lasts forever since it’s a property of the substance rather than something applied to the surface.
It worked well enough on my old Toyota (back in the dark ages when last I was a car owner) for me to drive without functional windshield wipers. In fact, unless someone splattered me with muddy water from a puddle, I got to the point I never used the windshield wipers–they just cut down on visibility by sliding in front of my face and made little different in the rain, which was beading and sliding out of the way and not interfering much with my vision.
I use distilled water & nothing else. It has no minerals in it to make water marks. Its filtered so there is no dirt in it. Cheap too.
I might add that the window beads up just fine using that kind of water.
BTW: Some professionals wash their car with distilled water as it has no minerals in it to make water spots 
I’ve been using Rain-X since the mid-70s. I’ve used it on everything from Saabs to SUVs, and the efficiency varies witrh the slope and shape of the windscreen as previously noted. The newer fomulation seems the “polish off” better than earlier versions.
The harder it rains, the better it works. The more you use your wipers, the more often you need to reapply it.
Works for me. 94 Honda Civic. Lasts about a month. Really comes in handy on the highway when blades are not that effective.
Has anyone ever tried car wax on their windshield? Is there any reason you can think of not to? It seems like it would do quite well at beading the water off the glass.
I used it when I drove semis (very vertical windshields.) It worked very well, though when you’re driving 3-4,000 miles a week, the constant reapplication got to be a pain. For rain, I find that just keeping wiper blades replaced before they wear out works the best.
The Rain-X was great for making it easier to clean 1,200 miles worth of baked on bug carcasses off the glass, though.
Or, one can just use a far cheaper substitute.
Try Armor-All and the like. (The one’s without the wax.) Lots of highly volatile oils.
Remember, just a few drops on a paper towel. Do not spray it onto the windows!
My dad would wax the side and rear windows of his cars, to help with water beading and such. He advised me to never use it on the windshield because the wax residue could refract oncoming headlights and make night driving dangerous.
I think Rain-X is an awesome product, I’ve used on four different cars, and I vouch for it.
My coats have always lasted about a month. However, it won’t last as long if there’s been an unusual amount of rain.
Anyway, here’s how I put it on:
But the shit is the best. I hardly ever have to use my wipers right after applying it.
As for their anti-Fog product, don’t get it- it sucks.
Worked terrific on my '93 Cavalier, works great on my '95 Probe. Lasted closer to two months for me.
The keys:
Get your windshield as clean as possible. I used to carry some in the car, and apply it just after coming out of a commercial car wash.
Put lots of it on and rub it in thouroughly. My arms ached when I was through.
As others have noted, you shouldn’t need to use your wipers much, so don’t.
Rain-x is also available in a windshield washer fluid formulation. It costs about $1.00 more than standard washer fluid, but it’s much easier to apply than the other version. Seems to work well, although it probably doesn’t last as long.