Which AC Delco Plugs for 12 year old Montana with 90K miles
 

Several forums say use AC Delco plugs to prevent misfiring etc. 2 AC Delco plugs listed. AC 14 regular Rapidfire plug and the AC 41-940 Professional Platinium. The AC 14 plugs are heat range 3 and the AC 41-940 plugs are heat range 4. I guess the 41-940 are hotter.
Engine not burning oil (leaking some). Which ones should I get? Car has 90 K miles and is 12 years old.

OEM plugs are 41-940. New plugs pregapped at .50 not .60
 

New AC plugs pregapped at .50 not .60 see new post