I will be gone 18 days and was wondering if any hotels close to LAX allow free 18 day parking with only 1 night stay?
Wrong forum I'm afraid, this is the TripAdvisor Support forum for questions relating to the use of the TA website. You need to ask again in the relevant destination forum, a link to the forum home page is below.
As a newer user of the forums, I would suggest before posting on any forum to read the "sticky" at the top of the forum’s page, if there is one. The sticky will explain the focus / purpose of the forum, important information, and other details. As an example, the sticky at the top of this forum is;
"PLEASE READ: How to use the Support forum!" and has a push-pin icon beside it.
I noticed that you inadvertently posted your question in the TripAdvisor Support Forum, so I have moved the topic on your behalf to the Los Angeles Forum.
The TripAdvisor Community
Many of them allow you to park with NO stay at all.
For 18 days though it may become less expensive to find an alternative way. Perhaps the train into LA or perhaps you can get a friend to drive you and then Uber back home.
This parking lot at the LA Hilton is very inexpensive.
I think for my 8 days I paid $60 which is certainly less than what I would have spent to book a room there:
Scroll down to see the best rates for your dates.