a standard spark plug should last 10-20K KM...those better/performance type should last 30-50KM....
Spark plug is wear and tear part...
Also life span of spark plug depend on your engine condition...if your engine makan engine oil / wrong tuning then your spark plug will wear out faster.
thanks 2 all sifu's here read my tread ..
want 2 sell my ck2a conv e6.5 but last 2 years u bought this car its already 4wd from johor..
and its pass puspakom test..
now if im selling worried about puspakom...