I use Areo Cosmetics
https://washwax.com/ and like it. Stuff is pricey but seems to be good. Wash with a quality car wash soap.
As far as extended warranties...The dealer sprang that on us at the last second. I didn't want but SWMBO was insistent on it, I lost. I am of the camp to put the premium in the bank for repairs. I think the reason they wait till the last second is so one doesn't research what a rip-off they are. In the mid 70's I worked for a heating oil/furnace place and the owners didn't hide the fact that they were a money maker.
Haven't used it yet. Hopefully never will happen.