1#Dish Detergent
People always take it simple when choosing detergent for the car wash...
some of them even use dish detergent
Do you know that
The first myth is that you can use dish detergent on your car. Yes, using dish detergent will get your car clean. However, it is not the soap you want to use. This is because dish detergent will actually speed up oxidation on the paint, and it will lead to a degradation of the paint job.
2#Shiny, not Clean
Many people believe that if a car is shiny, then it must be clean. This is a case of the eye seeing something, but not seeing the whole picture. You should feel the paint and if it is clean, it should feel glossy. Chances are it isn't, and will feel more coarse, like a sandpaper. If that is the case, the paint is not clean and needs to be cleaned more. Something like a clay bar would be smart and that will take off any problems.
3#Clay Bar
To follow the last myth, many people think that they can't clay their car. Claying a car is extremely easy to do. All you do is take the clay, spray a little on the area before you clay, and then rub. It will take out the problem spots on your paint. You can easily do this, and you shouldn't have to go see a professional for it.
4#Swirl Marks
Swirl marks are common on many vehicles. They are literally scratches in the paint, normally made by someone trying to get something off of the paint. It may accomplish the task, but you will scratch the surface and it will show, often badly, after a day or two. One of the myths is that waxing can get this out, but since it is a scratch, you are pretty much stuck with it. The only way to fix it is by a paint cleaner, or by trying to polish the surface.
#Smooth Equals Safe
This is a big problem. Many people clean their cars with anything that seems smooth. T-shirts, towels, napkins, you name it. The best and only type of cloth you should be using are micro fiber cloths, which are also used for things like glass and eyeglass lenses.
5#Waxing vs. Polishing
Many people think that they are the same process, but they are clearly two different methods of maintenance. Polishing makes a glossy surface on your paint. It will potentially remove some scratches, but it will make the car look great. Waxing is a layer of wax or other synthetic substance that will lay on top of your paint as means to protect it from rocks, dirt, and other debris. Coupled with this myth, is the length that wax holds. Some people think it can last a year, but that is not recommended. Along with that, just because your car is waxed, doesn't mean you can forget about it. You should have your car waxed a couple of times throughout the year so the paint gets maximum protection.
credit to:http://www.autos.com/car-maintenance/car-cleaning-myths-and-facts