Well, a 1987-amiga is close to being 20 years. I would actually guess a lot longer, if you are good at doing some maintainance. My A500 has gotten a rough treatment the last 8-10 years, beeing transfered a lot from cold to warm rooms and was even stored about 5 years in a house with no electricity. Never turned on those years. The temperature inside the room was probably below zero at the winter, and +20 degrees at the summer.
But it still works like a dream