I heard some car washes have soaps that are bad for wax and will strip it off, how true is that?
Yes, cheap soaps will break down the wax or sealant rather then preserve it. Remember, the average car wash deals with all kinds of cars, from cheap crap to nice Maserati's, so they often will use a more abrasive chemical soup to help breakdown the dirt and grime on the guy who never waxes/seals and washes his car once a month. In the end, the car always comes out clean…but for the guy who waxs/seals his car regularly, only mild soap should be used as the stronger soaps literally break down the properties of the wax/sealant. Also, keep in mind a sealant is stronger then a wax (although don't shine as good generally speaking) and some sealants are stronger then others.
The BIGGEST issue with car washes or at least the automatic car washes are the giant brush rollers they use rarely cleaned and pic up gunk from all the cars and end up creating fine micro scratches in the clear coat of the car which you can see if you look closely…same thing as swirl marks. Then you have to burn off a layer of the clear coat using a more abrasive polish compound prior to the next time you wax it to remove the fine scratches and swirl marks. Eventually this strips down the clear coat and the paint of the car underneath will start looking tired requiring more waxing.
It is best to hand wash the car and insure you or they (if you have it done) uses a clean wash mit/glove made of soft wool. Fine scratches and swirl marks are bound to happen, but the auto car washes or "tunnel washes" often contribute quite a bit to that.
Now, the BEST solution for the guy who doesn't have time to hand wash or wax his car 4 times a year, or use a sealant 2 times a year is to use something like Opticoat Pro. It is a permanent sealant that basically adds another layer on top of the clear coat that is highly scratch resistant and very durable protection. It is best to have a professional do this and it will cost $400 to $1000 to apply it. The range is dependent on the condition of the car. You HAVE TO polish the car before applying it and if the car already has scratches then the detailer will have to apply a couple levels of polish and rubbing compound potentially, then Opticoat and wax so your cost will be closer to $1,000. With Opticoat applied, you can still wax the car for a good shine, but just know you will not be able to achieve quite the depth and "liquid" look of a high quality low durability wax job, BUT your car will look much cleaner at all times (Opticoat repels dirt including break dust so use on your wheels too) and your paint is as bulletproof as possible without stepping up to a 3M clear bra wrap. Opticoat is a functional solution for a daily driver. Would I use it for a weekend toy i.e. Ferrari….no, but for a high-end daily I view it as a must. It will not stop the tiny micro chips from pebbles and rocks on the road from happening to the front and hood of the car, but it will take a harder impact to create the chips. Also, if someone tries to the key the car, they'll have to use twice the force and really dig in to do damage to the actual paint.
If you want to use auto car washes regularly because you don't have time to hand wash and or don't have time to detail regularly or drop it off for to a detailer a few times a year, then without question get the Opticoat done to it and just run it through normal car washes and wax once or twice a year and you are good. Even consider the clear-bra for chips.