After running 1-2 years (about20000 kilometers), the automobile engine will have performance degradation in different levels:

1. Economic performance degradation, fuel consumption increase
2. Short of power, fast acceleration not free
3. Start not smooth, especially in cold start.
4. Excessive exhaust emission
5. Noise increase
6. The engine oil turns black fast or even slightly burned

The reason of above phenomenon might be various, but an important factor which can not be neglected is that the engine has been contaminated. The accumulated carbon make the engine cant's work normally and coordinately, which resulted in a lower overall performance and the car no longer has a good manipulation ability. It also brings hidden danger to the safe driving.
The accumulated carbon inside brings a serious impact to the engine and shorten its service life. As we know, the three killer factors to the engine service life are: corrosion, abrasion and accumulate carbon.