WD-40 is essentially kerosene and a carrier/spray. Nice for cleaning
metal, loosening things up, etc., like a penetrating oil, but NO
long-term lubricant properties. For garage doors, etc., I use an SAE-80
gear oil, as it doesn't run as much, and pretty well stays where I put
it. The silicon lubricants are generally waterproof, but as the last
poster points out, they mess up the surface for painting, unless very
throughly cleaned. I use WD-40 for cleaning, but NOT lubricating
firearms, cleaning the rims of my bicycle wheels, and stuff like that.
I find that a pump oiler full of ordinary 10W30 motor oil really meets
the majority of lubricating needs around the house, plus the SAE-80
gear oil for stuff like the garage door pivots and the bearings on the
push lawnmower. A small grease gun is likewise handy to have around.