How long have the plugs been in their? Are they original? They just look like an old plug that needs to be changed.

Btw running a lower octane won't hurt anything but it is false economy. You engines computer will just adjust the timing so it won't ping but your power and mileage will go down.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200