My question is why does this engine ping and knock with 87 octane fuel. I shouldn't have to run higher octane with this engine should I? It is a 2001 hyundai accent gs 1.5 ltr sohc with 48 000 km on the odometer and automatic. Another thing I noticed about the shift stratagy of the auto is when I'm coming up to a yield sign and slow to a crawl the tranny stays in third gear unless I WOT it to make it kick down but then it just jumps to first and starts wailing why doesn't it ever shift down to second when I'm slowing then accelerating. I find that it just lugs the motor and increases the knocking and pinging. Or should I just run 89 octane and shut up and just drive the thing? for such a low hp motor it should run fine on 87 octane like the manual says.