When replacing spark plugs, do not adjust the gap on platinum or iridium plugs, as they are pregapped by the manufacturer and using a gapping tool could damage the electrode plating. A spark plug socket with a rubber grommet is necessary to protect the porcelain insulator and hold the plug during installation. Purchase new plugs and replace them one at a time, inspecting each for defects; any cracks in the porcelain insulator indicate that the plug should not be used. Remove engine covers and disconnect any hoses or components that obstruct access. For V6 engines, the upper intake manifold must be removed to reach the rear plugs. If the plugs have conventional wires, pull them by the boots, while those with coils require disconnecting the coil wiring and unbolting each coil. Use compressed air to clear dirt from the spark plug area before removal. A proper spark plug socket and extension are needed due to the deep recess of the plugs. Compare old plugs with those inside the back cover to assess engine condition, and apply a small amount of anti-seize compound to the threads to prevent damage during future removals. To avoid cross-threading, use a short piece of rubber hose over the plug to help align it with the hole; if cross-threading occurs, the hose will slip, preventing damage. Tighten the plug to the specified torque and securely attach the plug wires before reinstalling any removed components.