Changing plugs every 30K is so 1970.
Go get some double platinums or iridiums and be done with it for another 100K.
SOOOOOOOOOOOO TRUE ........... MY FORD has 130, 000 on factory plugs, runs GREAT! Didn't change my Mustang plugs until 150,000, because 1 was mis-firing.
IF it ain't broke .......... don't fix it. If it broke ...... fix it yourself or take it ANYWHERE but the dealer. Would ONLY go to dealer for warranty work.