In theory, a wax contains wax which stays on your car to protect your paintwork, and a polish contains abrasives which removes a tiny amount of dead and oxidized paint. In practice things might not be quite as simple as this because there are many products that can do both at once. And there is also the problem that the marketing guys can call a product anything they want and frequently do! Sometimes you can’t go by what it says on the front of the bottle, you will need to read the small print to see what the product actually does. I cannot stress this enough, waxes and polishes are different and do different things, but the marketing people don’t really care about definitions and will call a product anything that they think sounds good (Wax, sealant, glaze, paint cleaner, etc.). So it’s important to understand what the differences are, what you want, and then choose your product based on what it says on the back of the bottle, on sound advice and recommendations.
Polish
The purpose of a polish is to clean your paintwork and make it shiny again. A polish usually contains abrasives, this is most commonly aluminium oxide, as you put it on the car will remove dead paint which has become oxidized. They may also contain lots of solvents which clean your paintwork (paint cleaning products). Products do contain waxes and oils but generally speaking, these are there for lubrication of the abrasives and not enough to give protection to your car. In fact having polished your car you will have stripped back any protection you may have, so you will need to put a wax on your car.
I’m often asked how often you should polish your car, the best answer is to do it when it needs it - when the paintwork starts looking dull and tired. You shouldn’t really polish your car every time you clean it, if you do want to follow a schedule, then once every 6 months is enough for most people, but once a year is fine.
Wax
The purpose of wax products it coat your car in a protective, sacrificial layer. Wax products contain a blend of waxes and oils. The waxes can be natural waxes and/or synthetic, although there is a trend at the moment for the synthetic based products to be called Sealants*. Both types of product get attacked by road salts, UV rays, ozone and all the other nasties — but while they are bearing the brunt of this punishment, your paintwork doesn’t have to, which is why we call it a sacrificial layer. Waxes and sealants generally last from 1 month to one year, generally speaking most waxes last 3 months, be warned, they don’t always do what they say on the tin. Many waxes will promise that they last 1 year but they seldom last anywhere near that, so it’s best to assume you wax lasts 3 months**. The general rule of thumb is that the longer they last, the less shiny they are, and visa versa***. Waxes are designed for slightly different purposes, some people like to wax their car every week and want the best shine they can get, other people want to put it on and forget it for a year, they require protection and don’t worry too much about getting a ‘wet look shine’. There are even products designed to make a car really really glossy that will last a few days or even a few hours — this sounds crazy and impractical, but they are perfect for cars in a showroom or at a car show.
http://www.carcareadvice.co.uk/faq/exte ... polish.htm