i have the aluminum sides on our MH and I try to wax it at least once a year. I use Mothers wax liquid. Welcome to the forum. I also will use the spray detailer for spot clean up.
I've been using Turtle Wax instant spray for years. It's easy to put on and lasts all year long. It takes three bottles at about $5 each to do a 27 foot motor home. Just bought a 33-foot Class A so I'll have to buy an extra bottle.