I'm sure most of the guys in here would have an opinion about your
mentioning that the plugs don't need service for 100,000 miles; here's
mine FWIW:

Aside from the obvious risk of not being able to get the old ones out
after 100K; also by this time the gap in them is wider than hell,
shortening the life of the coil as it's working way overtime trying to
fire across that way-too-wide gap, and of course by this stage of the
game the vehicle is out of warranty so you're buying coils and etc as
well as hassling with the busted off plug(s)...

In other words, anyone who suggests that you don't need to change
plugs until 100K...FORGET THAT! :-)

Just my 2=E7