Some engines, in particular newer engines have the ability to recognize and retard the timing with repspect to the type of fuel used (actually with respect to whether or not the engine is "knocking", thus the "knock sensor"). Many vehicles are fine running on 87 despite it being recommended that they run premium. I know in my 92 SHO and in my mom Olds Aurora they said premium recommended and neither of us ever ran it with no negative results. That being said, if you are going to drop that kind of money on a WK Hemi, you might as well do what the owner's manual suggests and run 89, it's at most 10 cents more a gallon and a lot of places around here have it for the same price as 87.
Last edited by ajmorell; 03-13-2007 at 02:50 PM..