The viscosity and grade of motor oil is what interests us here. Viscosity refers to how easily oil lows. Two primary factors affect oil's viscosity: temperature and age. When oil is hot, it lows quickly. Oil lows slower as it cools. As oil ages, the polymer additives break down and the oil loses viscosity. Most vehicles require multi-grade motor oil. This means the oil has characteristics of both cold weather oil and warm weather oil. As an example, consider a vehicle that requires a 5W30 grade of motor oil. This means that the oil has the low properties of a 5-weight oil when cold and a low property of a 30-weight oil when warm. With more vehicle manufacturers employing variable valve timing systems on vehicles to meet emissions and horsepower needs, how well oil lows through an engine becomes very important. Many manufacturers use oil pressure or low as the power source to adjust the timing. If the wrong grade of oil is used or if the oil is old, the low properties could be insuficient.
Variable Valve Timing
Variable Valve Timing
