"11" is "wide gap." The "5" is the heat range; on NGK's, the lower the number, the hotter the plug.
The NGK 6240 (PLFR5A-11) was the factory plug in the VQ40DE engine up to 2007, when they switched to the Iridium. Ironically, Nissan still kept the service interval at 105,000 miles, which the Iridiums can easily surpass. Performance-wise, I've used both and haven't noticed any difference other than the price and longevity. I can get 6240's for around $10 per plug compared to around $18 for the NGK Laser Iridiums. Couple of notes: do not mistake the Laser Iridiums with the IridiumIX plug, which is an economy iridium plug with a service life of 60,000 miles. Also, beware of counterfeit Nissan and NGK spark plugs on Ebay. I got a set of Nissan plugs (PLFR5A-11 NGK) on Ebay and when I received them, I noticed a copper core inside the ground electrode; NGK Laser Platinum plugs are supposed to have a solid Nickel ground electrode. When I looked at the box, it had the NGK part number correct, but had the Nissan part number for the PLFR6A-11 plugs (I think it was 22401-01M16 instead of -01M15). So, stick to reputable part sources like Rockauto, Advance Auto, Autozone, NAPA, etc.My 07 Pathfinder and my 10 Frontier both had DILF plugs which are iridium, are the PILF plugs standard plugs?
If you go to NGK's site, it has a part locator. If you look up your application, it'll show all of the NGK plugs that will work in it and will footnote the original equipment plug. It also has part #'s for coil-on-plugs, ignition wires and oxygen sensors. They also have some good information on the site about their plugs.i had never seen any comments on the variations of iridium plugs, thanks for the good info as the learning never ends. i like to cross reference to a standard ngk plug when possible but prolly due to higher profits many sites do not show that!