CampingWorld has lost another Customer and refs for life!

As soon as you put fuel/oil the item is considered used.
As far as the CA law, there is an exception:
(b) This section does not apply to food, plants, flowers,
perishable goods, goods marked "as is," "no returns accepted," "all
sales final," or with similar language, goods used or damaged after
purchase, customized goods received as ordered, goods not returned
with their original package, and goods which cannot be resold due to
health considerations.