I don't want to answer for Mr. Brown, who has given you excellent advise. My answer is to just pull one pin at a time, squirt a little grease or a heavy oil in the top of the hinge hole and reinsert the pin in the hole. It will probably take you a few tries to get a feel for the right amount but too little is better than too much.
For what it's worth, light oils like WD-40 and 3-in-1 don't last very long and the WD-40 is gone very quickly. The lithium grease is the best choice.