If you have a car that’s been sitting in your driveway for a while, you’ve probably wondered what you need to do to get it back on the road. Or maybe you have a vehicle that you don’t drive very often, and you’re wondering how to maintain it.
The short answer is that oil does go bad– even if you’re not using it. For a full breakdown of how long it takes and why it breaks down, keep reading.
Typical Oil Shelf Life
If you’re strictly speaking about motor oil in its original sealed container, it can last up to 5-years. However, as soon as you open the container, the clock starts ticking – whether it’s in your vehicle or not.
Once you have opened the container, however, the oil is only good for another 12-months. So, if you use oil from a container that’s been open for 6-months, you should change it after it’s been in your car for 6 more.
Factors that Affect Oil Shelf Life
No matter if you have an open or closed oil container, there are a variety of factors that affect the oils’ shelf life. The most significant factor is the storage temperature. Ideally, you should store oil in a dry, cool environment between 40- and 85-degrees Fahrenheit.
Too much heat and the oil will go through a thermal breakdown process, which will reduce the oil viscosity and prevent it from grabbing enough contaminants as it goes through the engine.
On the other hand, if the oil gets too cold, it will start to sludge – which can lead to the oil breaking down.
Another factor that you need to consider is the type of oil you are using or storing. While both synthetic and conventional motor oil will expire, they do it at different rates. Synthetic oil will typically last a bit longer than conventional oil – but you still should never use synthetic oil 12-months after opening it or 5-years in a sealed container.
Why Does Oil Breakdown if It’s Not Used?
Once you have exposed the motor oil to the air, a process called oxidation starts. The oil molecules react with oxygen molecules in the air, and this reaction ruins the oil properties. Not only does it make it more likely for components to rust, but it also increases sludge formation and makes it harder for the oil to collect sediment that slips past the filter.
How Often You Should Change Your Oil?
While the mileage varies depending on what type of motor oil that you use, at a minimum, you should change your engine oil every 12-months, even if you’re not driving the car.
Summary
While oil that you aren’t using lasts longer than oil that you are using daily, it still expires, and you need to change the oil in your vehicle at least every 12-months. And while it’s typically safe to buy in bulk – once you have opened the container, it is only good for 12-months. Finally, even if it’s completely sealed, you shouldn’t use the oil if it’s been on the shelf for more than 5-years.
The oil might seem expensive – but it’s far cheaper than the cost of a new engine.