i use Fluid Film in the door locks, no issues.
I have my truck FF each year (2013 Toyota Tacoma ) which looks like new , recently had frame inspected by Tacoma as they have a program
to replace frames
due to a Class Action case because of problems with rust.
Truck passed even the manager that inspected the truck was impressed enough he called all of the mechanics over to see it .
If FF is good enough to protect the bottom of the truck it isn't going to be a problem in the door locks as it doesn't harden
TOMB