The ultimate car cleaning is the use of a clay bar, or paint clay to remove contaminants and dirt that you can't even see. If you are someone who uses clay to deep clean your paint, you know what I'm talking about, and you may proceed to the third paragraph. ;-)Why clean your car with clay?? If you've never tried it - don't worry, that's a legitimate question. Here's why - micro-dirt, oxidation, atmospheric contaminants, etc. can all become deposited onto and embedded into the surface of your car's paint finish. After you have just washed and dried your car, run your clean hand over the surface (even better to use the back of your hand). Feel that grit? You can actually hear it... catching on the skin of your hand - yet you cannot see it. This is where clay cleaning comes in.  If you are new to using clay, I strongly recommend looking at some videos on YouTube on how to do it. You can't really `harm' anything, but you can certainly make a mess and frustrate yourself if you're not familiar with the process.  I will summarize the key points and steps for reference:- Starting with a CLEAN car, freshly washed and toweled dry (even better if you have stripped off your wax.. tip: Dawn dishwashing liquid will remove all the wax):- Tear off a manageable sized chuck of clay.  Something that will be about 3" diameter when fairly flat is good.- Saturate the clay with Speed Shine - both sides. Don't worry about getting your hand wet, you'll be glad you did (or the clay will stick to your skin). Some people wear gloves - I do not. I like to feel the clay, and I know if it starts to stick to my hand it needs more lubrication. Lubrication is critical - the clay should always be WET with Speed Shine.- Working with small sections of the car (like a fender, or  of the hood, etc.) apply a mist of Speed Shine to the area to be treated.- Flatten the clay from a ball so that it forms a fairly thin disk. About 3" diameter and " thick is a good place to start.- Making sure the clay is wet with Speed Shine, lay it flat against the paint, and gently move it around the area you're working on. There is no need to follow any specific technique such as "back and forth" or "up and down" or "circular" - other than to ensure you don't miss any spots. DO NOT apply any pressure. Just enough pressure to control the clay is all you need, no pressing down. Re-we the clay and surface as needed. You will feel the clay "grab" or "stick" when it becomes too dry - spray it with Speed Shine and continue.- Occasionally lift the clay and inspect it. You will want to fold it over as it thins itself out with use - and/or as it picks up the dirt and becomes soiled. You don't want to drag the dirt back over the finish - so fold frequently to keep fresh clean clay in contact with the paint.- When finished with a section, use a mist of Speed Shine and a soft microfiber towel to wipe clean and lightly buff dry.- When done - some recommend re-washing the car. To me that is optional (you decide). But bear in mind that there is now NO WAX on your paint. You'll need to re-wax the entire vehicle now.As far as clay cleaning goes, there are two main parts - the clay itself, and the lubricant. I think most clay is about the same. Some are more or less pliable than others, some seem more porous - some smoother, etc.  I like the Griot's clay really well and find it easy to use. The amount supplied is very generous. I can get more than a year's worth of use from each container - often longer, depending how frequently I use it and how much stuff it picks up. The clay is nice and pliable, and I find it to be a good consistency - smooth enough to glide well on the surface and still porous enough to grab the dirt.  The most important component is the lubricant used. This is where the contest ends, in my opinion. I have used Griot's Speed Shine for many years. Not just for clay cleaning, but for nearly daily use to do a quick detail on the car, remove some light bird dropping or bug juice, etc. I even clean the glass (windshield too) with it. The stuff is just amazing. It will not harm anything - paint, chrome, glass, rubber, plastic - you name it, it is safe to clean with Speed Shine.If I could have only one product in my garage for car care, it would be Griot's Speed Shine. And for deep cleaning before waxing - the use of Griot's Clay is the best way to deep detail your finish.  Ten stars!