exterior plastic

Acetone will work. Wipe just once with a paper towel moistened with the acetone and then throw it away. Repeated rubbing will cause a mess. This is an agressive way to treat yellowing plastic but it will restore most weathered items, just take care.

Awesome, the stuff from the dollar store removes yellowing from plastic. However, DO NOT let it run down the sides of your rv. I tape some paper towels or shop towels under whatever I'm using it on. You can dilute it but it works better straight out of the bottle.

If it's white plastic that has "YELLOWed", spray it with water to which you have added some BLUE RIT® dye.

I've had good luck using softscrub with bleach to 'whiten' up exterior plastic-they also sell cleaners & waxes(turtle wax) now that are color specific-I've used the black cleaner and wax on my truck-will try the white line on the product next summer.