Engine Oil is essential for proper vehicle performance because it lubricates the engine. Without the right amount, type and texture of oil, your engine will not move freely and it may lock up at any point. Which could leave you stranded with an immobile vehicle! That is why routine oil changes every 5,000 - 7,500 miles are so important, if you wish to extend the life of your vehicle. Oil changes also present a chance to look at your car's fluids (like coolant and windshield wiper fluid), to make sure they are at the right level.