Champion Spark Plug Sales Symbols

Over the last few seasons the sparkplug manufacturers have had to change their recommendations for spark plugs for many applications and or come up with new designs. The biggest reason is that the fuel for sale has been changing due to federal regulation and new technologies.
It is not a safe bet, any more, to install the same plug that was in your motor from the last tune-up, for it could easily be inadequate for the current fuel being used. You probably won't hurt your motor by not upgrading, but you most likely won't be getting the best performance out of the fuel that you do consume.