NGK Spark Plug CPR8E NGK is one of the world’s leading spark plug manufacturers. As the factory-fitted choice of many vehicle brands, NGK is there when the spark starts to fade. You get an NGK standard spark plug, just like the one fitted to your vehicle. Heating value and plug construction are as the original. The service life of a spark plug depends on the fuel type, engine condition, driving time and the engine temperature. With 4-stroke engines over 250cc, spark plugs should be cleaned or changed after approx. every 6000 miles. With smaller capacity engines, in particular 2-stroke engines, this should be done after approx. every 2500 miles. Oily deposits start to build up after this sort of mileage and can cause starting problems and a drop in performance. The intervals can be shorter where bad quality oil is used, or the journey time is quite short.