I have a 03 G35 Coupe, The Manager down at my local Infiniti dealer parts and service told me there is no reason to change the spark plugs on my car EVER! Is this true???? I had my car since 03 and never changed the spark plugs just your usual oil changes,air filters,brakes,tires, but nothing major because this car is that dependable, but i have never changed the spark plugs. Can someone please give me some more info on spark plugs for my car, What brand i should get? Is this a do it yourself job?.....Stuff like that, Thanks.