The center rail, which cocks that hammer as the slide moves rearward, and has to slide over each cartridge as the pistol cycles, needs to have a light coat of lube applied. If you have a series 80 style pistol, you also need to apply a light coat of lube to the firing pin plunger hole. A very light coat of lube can also be applied to the firing pin hole. All parts can be wiped with a light coat of oil. If you are using light weapons grease, use it only on the bore of the slide and locking lug grooves as well as the slide rail area.
Oil is recommended on all other areas of the slide and the internal parts.
Grease is especially suited to the high load areas such as the bore of the slide and the rails, but is a little too heavy for the small parts that exert only a light bearing load as they function. The frame comes next. If you have completely disassembled the frame, all internal components should be given alight coat of oil before reassembly. Once again, if you have light weapons grease, the frame rails are the only area that needs that type of lobe. Let's not forget magazines.