Oil is the lifeblood of your vehicle. It keeps the many components of the engine working efficiently, and it helps reduce the accumulation of varnish and carbon from collecting on the engine. As you’re aware, the engine can get very hot from the thousands of small explosions taking place every minute; oil helps pull the heat away from the combustion chamber essentially preventing the engine from blowing up. As oil collects heat, varnish and carbons during the course of protecting and keeping the engine running smoothly, it eventually becomes less like liquid and more like sludge. No matter how good the oil is, eventually, it degrades as the additives get used up. That’s when you should have your oil changed.