Some real bad advice being given out here.
Odds are your pinging is because of carbon deposits in the upper cylinder head area. Higher octane will mask the problem but at the same time speed the rate of carbon accumulation. Hunt online for a source for a product called "44K", it's made by a company named B&G (www.bgprod.com).A professional mechanic friend recommended one can every 3 months to remove the deposits and it's worked.
