The primary job of motor oil is to eliminate friction within the engine. By doing so, it not only keeps the engine operational but also prolongs its lifespan. However, sludge buildup due to a defective crankcase ventilation system and accumulation of different types of contaminants could kill the engine of your Volkswagen GTI. So, symptoms of engine sludge buildup in your vehicle should not be neglected. Have a look at this graphical presentation to get a broad awareness of it.