It lubricates until it evaporates, which it will do. It was designed as a water dispersant hence "WD" Its great for the company if you use it as a lubricant, because you will have to keep using it and buying it as it evaporates. IT is great for things that get wet that should'nt ie pocket knives it the wash etc.
I use lithium spray grease in my door locks.
Don't get me wrong, i use wd-40, i just don't use it as a lubricant. If i need a penetrating oil its okay, i have used it to clean off tools. and dry things that should not have gotten wet.