any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking

any of various compounds that are added to gasoline to reduce engine knocking