91Q plug replacement interval ?

[yidal8]

What is the max. milage I can expect from my plugs .

[Q45tech]

Depends upont the condition of the rings and cleanliness of intake and injectors and O2 sensors [whether the engine[injectors are getting the correct AF ratio [charge].

Infiniti's recommendation of 4 years or 60k was to make sure the plugs didn't sieze in the threads destroying the heads. Plus the interval to check the valve covers for leaks into the plug wells causing coils to become streessed and fail.

Plus how smooth you want idle and how tolerant you want knock protection............in any case they should absolutely be removed every 100k or 6 years!