well only one day 1/4 down from full tank of the higher octane 91 and the winter gasline antifreeze. i notice that i do still have a ping AT TIMES and RATHER lower in volume with none LOADS in the car. and only occurs with tramping on gas for a second. i know it maybe too early yet to see what effect on this pinging ( if any ) the higher octane 91 gas + gasline antifreeze + plus added today stp 2 in 1 octane boost that cleans also.