The manual for my Honda Jazz 1.3 Hybrid (2012) says that it takes NGK DILFR6F11G spark plugs. Can I use any other spark plugs, such as NGK LFR6ARX-11P or LFR6AIX-11? I assume that the "6" for heat rating, the "11" for gap distance, and the Iridium, are all important, but I don't understand what the other letters mean. What is the difference between regular Iridium and "Iridium RX" or "Iridium IX"?