Ok I have 55k miles on my stock AC Delco Spark Plugs Platinum, I have taken them out they still look alright but I think the gap might be a little too big. If I measure it to the factory specs and find that it is to big, can I change it? Would this have an effect on the spark plug in terms of getting more life out of it since its supposed to last until 100k?

Someone can correct me if I'm wrong -

Late model cars like yours are firing with somewhere
around 25,000 volts....this leaves plenty of voltage
to jump an extra wide gap, like an 80 thousands gap.

Do not believe you need to do anything if the used
plugs are under 10 thousands too wide.

Get a gapper and check them. You should be able to bend them in a bit if it is too wide.

ok i think that should be alright, I just want to improve the effiencey but i don't want to spend 50-60$ (locally) for spark plugs, i can get NGK's for 15$ but I don't want to waste any money if it'll make my engine run like garbage since NGKs platinum plug is different from the AC version.