Prepping for a winter trip so I bought a jug of Rain-X All Season washer fluid; the orange stuff at O'Reilly's. I figured name brand was worth a buck more than the store brand blue stuff. Then I found a few negative comments on Amazon about it congealing on the windshield and ruining the electronic sensor in the reservoir in Euro cars. Has anyone had experience, good or bad, with orange Rain-X in a 955? I'm 120 miles from a dealer, so OEM fluid isn't a convenient option.

 

I've never had issues with RainX except from one time where a car had the summer stuff and the weather dropped. It burst the lines but that's not really the fluids fault.

I​ get the lowest temperature rated fluid I can get. Usually -49C rated or so. I've never noticed a performance difference beyond the temperature ratings which make a huge difference.

Lower rated stuff will melt frost better and are less likely to freeze when the weather drops.

The brands all seem about the same beyond that.

I personally buy cases of BMW OEM fluid because I can get it for about $1 a bottle compared to $5 a bottle for other brands.

 

I've heard the same thing about the potential issues so my jug of Rain X is sitting in the garage and I'm using the cheap blue stuff.

 

I don't like Rain-X fluid or their windshield treatment. The treatment works great for a couple weeks, then the wipers start to hop and chatter, then if you look closely, you can see accumulated windshield wiper rubber at the transition point near the driver's side A-pillar where the wiper changes direction. Also makes for a very bad whiteout effect for a second right when the wipers run. Rain-X treatment does work well on the side windows though to allow water to just run off - even helps to keep frost and snow from sticking if you live where it's cold in the winter - it just doesn't work well on the windshield or play nice with the wipers.

Here's what I've found to be the absolute best wiper setup. Keep your OEM wiper blades as they have the perfect shape, angle, etc for your windshield, BUT, buy PIAA silicone blades in the appropriate size for your vehicle. Slide the actual silicone wipers out of the PIAA blades and install them into the OEM blades. Precisely follow the windshield prep instructions that come with the PIAA silicone cloth in the sealed pouch that was included with the PIAA blades.

You will have completely silent wipers that clean phenomenally well in both heavy rain and the lightest mist - no chatter, no missed spots, etc

I use Prestone Bug Wash as my reservoir refill - it's green and supposed to have something in it that helps loosen squished bug carcasses from the glass, but really, not much sticks once you've used the PIAA treatment.

 

The lower the temp rating of the windshield washer fluid, the higher the concentration of methanol. Some also have ammonia. Alcohol and ammonia are known to break down plastic and rubber. You would think the manufacturers fully plan/design for this, but that is a big assumption. They don't give a hoot what happens after the factory or CPO warranty expires. Ask guys running 100% methanol injection systems how tough it is to keep them from leaking. It is hard on your wiper blades, cowl, headlights, headlight washer system, and other plastic parts it contacts as it drains down.

The best thing you can do is use the lowest temperature rated fluid for your environment necessary to minimize the breakdown. If you like science you can buy the lowest rated stuff and dilute it yourself with distilled water.