As we get closer to Memorial Day weekend, there’s closer focus on gas prices for the heavily-traveled holiday period.  For the moment at least, fuel flows about 25 cents cheaper per gallon than this time in 2011, according to AAA.  That’s also about the current price gap between regular and premium, give or take.

Some drivers are doubling-down their savings.  They’ve stopped running higher-grade gas in favor of the lower-octane option.  Though as the Los Angeles Times cautions, saving a little now could come back to haunt motorists down the road.

Engine knock, characterized by a metallic pinging sound, can occur when an engine is under load and things get out of sync in the combustion chamber, with misfiring low-grade gas often the catalyst, so to speak.  It’s not a beautiful noise, and it’s not at all good for an engine’s health.

Cars today are equipped with knock sensors to…