How Often Should Engine Oil Be Changed for a Car That Is Not Driven for a Long Time?
2 Answers
For cars that are not driven for a long time, the engine oil should be changed every six to eight months. The details about engine oil are as follows: Classification of Engine Oil: Automotive engine oil is divided into three types: mineral oil, semi-synthetic oil, and fully synthetic oil. Mineral oil is the most basic and cheapest type of engine oil, generally classified as SJ or below, and is only suitable for low-end cars or some new vehicles. Functions of Engine Oil: Lubrication to reduce wear: There is rapid relative sliding between the piston and cylinder of the engine, as well as between the main shaft and bearing bush, which can easily cause wear. High-quality engine oil can form a sufficiently thick oil film between the two sliding surfaces, separating the surfaces of the relatively sliding parts, thereby achieving the purpose of reducing wear. Cooling and temperature reduction: Engine oil can bring heat back to the oil tank and then dissipate it into the air, helping the radiator to cool the engine.
I've always been an experienced driver and have dealt with many long-idle cars. Take my old BMW for example—it sat untouched for nearly a year. When I checked the dipstick, the oil had turned black and thickened, with a sour smell. This indicates the oil oxidized and deteriorated during storage, absorbing moisture from the air. Increased acidity compromises lubrication and can severely damage engine components. I recommend changing the oil at least every six months to a year, especially in humid climates. Don’t assume inactivity spares the oil—stagnation allows contaminants to settle, accelerating degradation. For extra safety, I start the engine every few months and let it run for ten minutes to circulate the oil. It’s a cost-effective trick for peace of mind, avoiding costly overhauls that could run thousands.
