Cleaning your paint does not mean washing your car, it means removing oxidation and contaminants, adding emollient oils back into the paint and smoothing out the surface of the paint. There are several products on the market that will accomplish one, two or all three of these functions.
In fact, there are so many products by so many names, that the correct choice may be confusing. Before we start, let's define some broad categories of products.
CLEANER: A cleaning agent may be either friction or chemical. A friction cleaner is usually either a silicate or clay particulate. If you examine your paint through a microscope, it would look like a mountain range with peaks and valleys. The friction or abrasive (don't get nervous at the word abrasive) type cleaner will clip the tops of these mountains off and help fill in the valleys, to approach the optimum smooth plane that offers the greatest depth of shine.
Friction cleaners are usually described as fine, medium or heavy cut. When in doubt, use the least aggressive product. A chemical cleaner will usually strip equal amounts of hill and dale and thus not help smooth the paint.
A cleaner should also remove old wax and other contaminants in the paint. Chemical type cleaners are usually more effective in removing the remains of 100 M.P.H. bugs, stains, tree sap and tars. Avoid silicone-based products as they are not beneficial to paint and can cause problems down the road. Ask any professional car painter their thoughts on silicone products, and you will usually get a 30-minute tirade.
GLAZE: A glaze usually denotes a superfine friction type of cleaning agent, usually with essential emollients and lubricating oils and may even contain some mild chemical cleaners. Glazes will usually remove mild swirl marks, scratches, refresh the paint with oils and smooth out the finish.
POLISH: A polish is normally a non-abrasive product based on a nutrient oil matrix and may or may not have a chemical cleaner as part of the package. Most polishes use fillers to help cover swirl marks.
COMPOUND: A compound is the "coarse sandpaper" of the paint-cleaning world. This should be used only if the paint is in serious trouble and all else has failed. If you are one step away from 1-800-NEW-PAINT, then you may consider a compound.
CLAY: Literally a plasticene/abrasive mixture used to smooth new paint and remove over spray. This type of product must be used with lots of lubricant. The technique of using a clay is a learned skill. Use too little lubricant, or get contaminants in the clay, and you have moved into scratch city. This is one product that is the fast lane to trouble if not used with extreme care.
Note: Clay is NOT damaging if you use a light grade. Clay is also suitable for old paint and does not remove a layer of paint. It removes contaminants from the paint. Any amateur using reasonable care can buy a Meguiars or Mothers light Clay Bar kit and successfully use it on a vehicle without damaging anything.
CLEANER/WAX: A combination, one-step chemical cleaner and a wax. I am not a fan of these types of products, as they are required to perform two very diverse functions simultaneously. A cleaner should remove old wax, so how does it simultaneously apply a coat of new wax? You may wish to use this type of product only in emergency situations or on your Yugo.
WAX: There are two broad categories of wax, organic and polymer based. The organic waxes may be derived from plants such as Carnauba, or varmints, such as bee's wax or some of the K-Mart specials contain paraffin refined from dead dinosaurs. The polymer-based waxes are usually collected from specially trained robotic bees that gather the polymer nectar from plastic flowers (or it may be made in chemical factories).
DEGREASERS/TAR/BUG REMOVERS: These types of products are normally solvents designed to dissolve surface contaminants such as road tar or bugs. There are two broad classifications of solvents, petroleum distillates and citrus based. The quality citrus products tend to be gentler on the paint. Any degreaser/tar/bug remover will remove wax. So after you have rid your car of the remains of Billy bee, you will have to rewax the area. (What is the last thing that goes through a bee's mind as he slams into your windshield at 60 mph? ......His stinger.) Be aware that many of the popular over the counter tar removers are based on kerosene and may cause long-term damage to paint.