If your car has been parked for a while, you might wonder whether the oil sitting in the engine is still good. Maybe you’ve only put a few hundred miles on it since your last oil change, or maybe it hasn’t been driven at all. While oil doesn’t exactly “expire” like food, it does degrade over time. And when it sits too long, it can cause just as much trouble as driving too long between oil changes. Why Time Affects Oil, Not Just Mileage Oil is designed to protect the engine by reducing friction, carrying away heat, and preventing metal parts from wearing down. But even if the car isn’t being driven, the oil inside is still exposed to air, moisture, and temperature changes. These things break down the oil’s chemical structure. Over time, it loses its ability to lubricate and protect engine components the way it’s supposed to. What Happens to Oil When a Car Sits When a car sits for weeks or months, the o ... read more