Originally Posted by Bucko
But how low for an engine designed to use premium? In high altitude areas, the octane of all grades is reduced because of lower amounts of oxygen in the air. I'd surmise you can still get an engine to ping at high altitude by running too low an octane.
Note to Tmex: you can't always hear pinging and the damage may take some time to show up. Keep us posted.
Bucko, I can hear parts pinging when I clean them in low octane gas.