Abbreviations O

O.D. -          Outside Diameter O/S -           Oversize O2 -            Oxygen O2S -          Oxygen Sensor OBD -         On-board Diagnostics OBD I -       On-board Diagnostics One OBD II -       On-board Diagnostics Two OBD III -      On-board Diagnostics Three OC -           Oxidation Catalyst OD -           Overdrive OE -            Original Equipment OEM -         Original Equipment Manufacturer OHC -         Over Head Camshaft OHV -         Over Head Valve OS -           Oxygen Sensor oz. -            Ounce ozs. -          Ounces