When a garage door spring breaks, everyone in the house will hear it because it’ll make a great big crack sound, but you won’t know what it is until you try to open your door. The average garage door spring or torsion spring has between 75000 and 100000 cycles, which is opening and closings. This is typically 7 years or so, but some people go through springs every 3 or 4 years, and some of them last decades! It’s essential to get the springs that are right for the door, though. Some companies will install undersized springs knowing that they will break prematurely, and sometimes they just install cheap ones.
Keeping the springs lubricated or oiled can help by eliminating friction where the coils of the spring rub against each other. If the springs begin to rust the will make a scraping sound.
It is advisable to get both springs changed when one breaks, because it’s only a matter of time before the other one goes.