I don't think there is any general answer - you have to check each manufacturer and sometimes individual product lines, e.g. motorhomes vs towables.
From what I read, the Jayco warranty is to the original owner only. However, the separate warranties on appliances or motorhome chassis components may be honored the the component manufacturer regardless of who is in possession.
Thor Motorcoach says their warranty covers the first and second owner only.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL