Washing the Car

Go to your local autoparts store and pick up some car wash soap. Meguires and several other companies sell car wash soap. The secret to the stuff is that it doesn't remove your wax, what a concept eh? If you use normal dish soap, kiss all that hard work good bye. You want to use as little as possible or you will still remove some of the wax. Use lots of water and little soap.

Matt Trostel writes about water spots and washing your car:

I don't usually have this problem on my Super Black '92 SE-R.   Here's some tips that might help.

• Don't wash your car in direct sunlight.  Even when it's in the 50's outside, a black car absorbs enough heat to evaporate water pretty quickly.   Evaporated water is the cause of most spots and streaks which are deposits left behind after the water evaporates.
• The Absorber (or any chamois) doesn't soak up all the water.   The mere fact that the chamois is wet means it will leave a little water behind.   My Absorber does the same thing: leaves a thin film of water behind which leaves smears (not exactly spots or streaks), especially noticeable on the windows.  You can get rid of this by using a     towel immediately after the chamois (ie. chamois half the hood and then towel it; if you do a bigger area, the water left behind may evaporate before you get to it with a towel).
• I don't know what type of towel you're using but old bath towels work well for me.  Darker ones don't leave noticeable lint.  Don't let the towel get too wet or it will leave streaks of water behind. I either drive the car a couple hundred yards or open the hood and the trunk to get excess water off after rinsing.  If you don't do this, you'll have to use 2 bath towels to dry the car because 1 gets too wet.
• Sometimes I'll go over the car (usually just to get dust off) with a spray bottle of water and a dry towel.  This works well for water spots, too.

These tips are assuming that the water spots are from the most recent wash.  If they're old water spots, you may have to do a multi-step clean/polish/wax process to get the water spots off the finish.

Special care should be taken to not get water in the spark plug wells. It will cause rusting and corroding of the contacts. There are two ways to avoid the water problem:

1. Use compressed air to remove moisture once it gets into the plug wells.
2. When washing your car, either jack the car up so that the water runs off, or park on an incline so that the water runs off.

Searl Tate writes about cleaning under the hood:

Unless you live in a high mineral/salt area, I advise against it. Taking cues from Mike Kojima's immaculate bay, I used his technique.

Just get a bucket of water, and a couple of paint brushes of varying sizes. For cleaning solution, I used both citrus cleaner and "Simple Green" on separate occasions. I prefer the latter (buy a big Price Club size and dilute it). My best results came from about a 30:1 mixture for dusty areas, and closer to 2:1 for oily spots (be careful where you spray the concentrate). Use the appropriate size brush for the job and use water sparingly. Another device that worked well for me is a "dishwashing" style glass cleaner (long handle). I have two- one with a brush, and one with a sponge head. A large spray bottle with clean water and adjustable nozzle works well to rinse tight areas. Shop towels or durable disposables work well to catch the rest.

Do this, and you don't need to worry about over spray and damaging components.