I thought they get week. So I changed my stock one about 6 months after break in. About 7-8 gallons of fuel later I have yet to replace it. I bought my truck in 2004.

So my answer is it may get weaker, but it either lights the fuel or doesn't. I can't see why a there would be any difference. Perhaps a little more difficult to start on cold starts but once light you should be good to go.