From micras owner manual:
“ Using unleaded gasoline with an octane rating lower than recommended can cause persistent, heavy “spark knock.” (“Spark knock” is a metallic rapping noise.) If severe, this can lead to engine damage.If you detect a persistent heavy spark knock even when using gasoline of the stated octane rating,or if you hear steady spark knock while holding a steady speed on level roads,it is recommended that you have a NISSAN dealer correct the condition. Failure to correct the condition is misuse of the vehicle,for which NISSAN is not responsible. Incorrect ignition timing may result in spark knock,after-run and/oroverheating, which may cause excessive fuel consumption or engine damage. If any of the above symptoms are encountered,have your vehicle checked. It is recommended that you visit a NISSAN dealer for servicing.
However, now and then you may notice light spark knock for a short time while accelerating or driving uphills.This is not a cause for concern,because you get the greatest fuel benefit when there is light spark knock for a short time under heavy engine load.”
First and second part of the statement doesnt go together.
Hypothetically if we consider this scenario:
What if you are driving to work at increasing steep angle? Lets say i live in area where to reach to work i have to drive 20km uphill. Angle starts to increase 1 degree at each km km and im carrying maximum recommended load in the vehicle and because of environment in that area there is wind blowing at 35-40km/h in opposite direction of my driving direction. So that means i have uphill+gradual acceleration to compensate for wind and increasing angle of the steep. It falls it first statement or 2nd? And am i now misusing the vehicle as per first statement in manual and am out of warranty?