NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
There's no need for sealant because the rubber ring around the thermostat creates the seal. Many new thermostats will come with the seal, including the genuine Nissan part # 21200-6M43A. FYI, the original thermostat is made by Fuji Seiko and I recommend sticking with the genuine Nissan part, as well. The correct plugs (as in the same from the factory) are NGK Laser Platinums #6240. It's due at 105,000 mile intervals. If you wanted a copper option, you could go with an NGK V-Power # 6376, but it would have to be replaced at 30,000 mile intervals. Also, don't put any anti-seize on the threads of the new, NGK plugs. NGK advises against it and it's not necessary as the plugs are plated.