Originally posted by ILuvDetailing:
Plugs for Nissan X-Trail? Denso or NGK? It says in the Manual:
Standard -> LFR5A-11
Service Option -> LFR4A-11
Service Option -> LFR6A-11

Based on NGK catalog, a LFR5A-11 means:
L- plug type, thread reach 26.5mm
F- shell size, 14o x 19mm, 16mm hex
R- resistor
5- heat range number
A- special design
11- spark gap, mm

This is a standard plug since iridium plugs starts with I or IZ, platinum with P, PL or PZ. The LFR6A-11 is a colder plug for long, fast hiway use.