The statement in my latest owners manuals says that warranty will not be denied by failure to keep receipts alone so I don't worry about it. Also of the warranty claims I have had to make to a dealer and family members who have had to as well, receipts were never asked for. This includes a bad lifter in my uncles F-150 truck that happened near the end of his factory warranty. Engine inside I guess was clean enough from regular oil changes they replaced it free of charge.