Quote Originally Posted by Knappster View Post
The upper 8 plugs are due at 30,000 miles, I cannot remember the the miles for the lower 8 plugs but someone will find it I am sure. But my bet is at 85,000 you might as well do them all.
You are describing the plugs in the 4.7L engine and not the Hemi that GP has. On the Hemi, all the plugs are on the top, side-by-side. In fact, there is a single coil pack per cylinder that has 2 boots coming out for the 2 plugs per cylinder. When I was changing my plugs, it was difficult to pull the coil packs off of 2 of the cylinders. On both of those, each coil pack left 1 boot in the cylinder head. It was a royal PITA to get them out! Make sure to use dielectric grease on the boots when reinstalling!

BTW, I did my plugs at 30,000 and put in Autolite Iridiums. With conservative driving, I can get 19 - 21 mpg on the highway with gently rolling terrain.