Oil Changes
Intervals, oil grades and why the 3,000-mile rule stopped being true.
Engine oil does four jobs at once: it lubricates, it cools, it cleans, and it seals the gap between piston rings and cylinder walls. It stops doing those jobs when the additive package is spent, not when the oil looks dark. Dark oil is oil that is working.
Almost every engine sold in the US since roughly 2010 is specified for a full synthetic oil and a service interval between 7,500 and 10,000 miles. The 3,000-mile interval belongs to conventional oil in engines that mostly stopped being built two decades ago. See how often you should change your oil for the interval that actually applies to your car.