@Laura2592 Wow, how odd that a guest who's stayed several times would suddenly have issues with things that he was able to figure out in the past. It almost sounds like he has some health-related mental issue going on, like Alzheimers, or even something like a brain tumor, that would make him act out-of-character. Or maybe he's on some medication that's making him confused.
I don't find it odd he'd ask for a recommendation of where to get his oil changed, though. It doesn't seem much different than asking for restaurant recommendations or anything else in an area a guest isn't familiar with.
I don't know what to suggest as far as reviewing or blocking from booking again. I'd almost be tempted to private message him and say I'm a bit concerned about him, as he had trouble with things at your place this last time that he didn't have any problems with before.
I guess it could just be a case of him starting to feel over-familiar with you and less reticent to complain. But these don't really seem like complaints that he expressed, rather than sudden and inexplicable confusion or inability to focus.