Hi guys , just bought a 87 gn from original owner in Ohio , car has 76000 original miles the owner hardly drove vehicle in past 10 yrs due to health reasons , car is in excellent condition motor ? Upon road testing heard knock from engine when I got on it , so I laid off didn’t want to push it , owner said he always ran 87 octane ... and the fuel is old , Should i pump out the fuel and run 93 in it and drive it gently for a tank or two then change plugs , fuel filter , coil pack wires and knock sensor? Want to keep it stock to certain point , just don’t want pinging if I want to get on it once in a while , thanks guys oh yeah I’ve been reading scanmaster is on the way