In most cases, dishwashing soap is the worst thing to wash your vehicle with. Because dishwashing soap is loaded with grease-cutting agents formulated to get your frying pan sparkling clean, it also removes any good oils and waxes from paint surfaces. After washing your car with dishwashing soap, your paint is wide open for damage from a variety of contaminants with no layer of wax to protect it.
There are rare cases where spot washing with dishwashing soap is acceptable. These include repairing small scratches and abrasions, removing thick stains from sap and repairing bird dropping spots. Always re-wax any area you've washed with dishwashing soap, and only use dishwashing soap when specifically directed.
For the most part, no. Any towel can get your auto dry, but not all towels can get it dry without leaving swirl marks. Clean chamois, 100% cotton terry cloth and microfiber cloths are the safest towels to use for car care, as they've been tested to treat your finish without creating abrasions.
When you use an old t-shirt, shop rag or cloth diaper, you're risking abrasions with towels that may have embedded particles of dirt. Or, they may be of a fabric blend that's not soft on your paint. The best way to dry your ride and minimize the risk of scratches is to get a set of safe towels that you keep clean and separate from the rest of your rags.
Once water spots are on your paint, the best way to get rid of them is to rewash the area. If you didn't dry your car right, you could have water spots everywhere. Ever hear the tired phrase, "an ounce of prevention is worth a pound of cure?" Don't ignore it this time-prevention really is the best way to deal with water spots.
First, carefully pick the place and time you wash your car. Staying out of the heat and direct sunlight is critical to avoiding water spots. Next, be sure to dry your ride immediately after washing. Don't let it air dry, and don't try to drive it dry. The only way to get the most out of your car wash is to take the time to dry it right and prevent water spots.
If you happen to get water spots on chrome trim, try rewashing the area to remove them. If the outlines are still visible, try using the corner of a rag soaked in white vinegar. This usually breaks up the water spot and leaves endless reflectivity on your trim. Wash the area after, though-you won't want that vinegar smell hanging around.
For most vehicles, opening your hood and turning the hose on full blast is a really bad idea. What used to be a gem of auto shop teaching advice is now a terrible idea, thanks to modern electronics that dominate your engine compartment. The same tactics that were great for keeping the dirt from settling on a small-block Chevy V8 three decades ago would absolutely ruin a modern Impala.
To clean your engine compartment without causing costly damage, you have two choices: carefully spot clean with heavy degreasers (being extremely careful not to get these degreasers on your paint), or wrapping all exposed electrical connections with plastic and spraying with a hose. Be sure that if you have a performance air intake with an exposed filter that it stays dry, too.
For most wheels, household cleaners are not recommended for use. They contain acids and other solutions that cause damage to the surface and streaks in plated finishes. The best cleaner for all wheels is soap and water or a wheel-specific degreaser.