Cleaner For Plastic Sinks

Liquid Spic and Span- Not the powdered type.
That is what my wife has always used.
Guy

NOTHING that is the least bit abrasive. Dish soap and water or cheap shampoo works great.

Ken

You could try toothpaste. It's mildly abrasive though.
I used it to clean up an outdoor thermometer that yellowed with age. Worked out great.

parapapam

Car polish - Turtle Wax, Meguiars, etc. Cuts through the stains easily.

I just use Clorox wipes.

I use ordinary baking soda and a bit of dishwashing liquid. For stains, I make a paste of ordinary baking soda, dishwashing liquid and cheap hydrogen peroxide (apply and let set for a few hours or even overnight if a bad stain). But I'm cheap (or frugal depending on how you view it). Most RVers opt for some expensive product that will do the same thing. Doesn't matter what you use just make sure it is VERY mildly abrasive as plastic sinks tend to scratch easily. The shiny ones really scratch easily. Don't use an abrasive sponge either. Wet cloth or sponge is all you should be using.

If it's hard water stains, use plain white vinegar. place a paper towel over the hard water stains, wet it with vinegar and keep it wet for several hours. It may take a few treatments but that is easy on a plastic sink. Then get in the habit of wiping the sink down at least once a week with vinegar.

I keep vinegar in a trigger sprayer bottle and I put a trigger sprayer top on the hydrogen peroxide bottle.

Wife uses "Bar Keepers Friend"