Accumulator said:
Wash it when it's dirty eough, clay it when it's contaminated, polish it when it's marred, wax it before it needs waxing.
As always, Accumulator's advice is spot-on.
My black daily driver is now garage-kept, which is a blessing and makes my life so much easier.
On the average I wash my car every 7 to 10 days. Sometimes more frequently if it's been raining. I have discovered the hard way that if I do not attend fairly quickly to the water spots that form after a shower, I will end up with etching in the paint.
I clay on the average of twice a year. I follow-up the claying with a paint cleaner or machine-applied polish, if correction is needed.
What wax/sealant looks good on black? To be honest, every wax and sealant I have used on my black car looks good. For a relatively inexpensive sealant, I recommend Mother's Reflections, which can be purchased through Amazon.com for only $11 a bottle. It's easy to apply and remove and confers deep reflectivity on my black car. I like it. I don't use it much anymore, though, as I'm going through my boutique wax experimentation stage. I particularly like Pinnacle Souveran; but it's prohibitively expensive, and durability is not very good. If you are tempted, wait until AutoGeek offers it on BOGO.
For a paint cleaner, you might get yourself a bottle of Four Star Ultimate Paint Cleanser. Dom Colbeck of Dodo Juice recommends that the paint on a daily driver be cleaned every 3 months or so. This seems like good advice. Certainly the car should be cleansed every six months. Another possibility is to use a cleaner wax regularly, topped with your preferred wax/sealant (see, e.g.,
Your Daily Driver).
Good luck and have fun!
Cheers,
Al
But there are a lot of things I prioritize *way* above washing the cars.