Dear H 49;
I usualy don't get into these debates, but Gearhead & Mike are "right on" here.
After over 50 years of working in the automotive repair industry; It makes no difference on which brand, as long It's of high quality.
My personal way is to use the (brand) that came with the vehicle ie; AC in GM, Autolite in Ford, Chysler & AMC. Champion in industial & stationary engines and NGK in the Japs.
As mentioned; the heat range is the important factor to consider which is learned when the old/used ones are removed at tune-up time.
The 6 cyl Chev uses an AC 45. If you start there the rest can be learned later after the vehicle has been driven a while.
Good luck, Johhn M.....
