Engine oil is vital to keeping an engine lubricated and functioning correctly. In a car that is due to be parked for a long time without use, it is right to question how long does oil last in a car not driven?
Engine oil has a shelf life, usually printed on the oil bottle. It is correct to assume that the oil still has use if still within its bottle expiration date. But what if you don’t know the age of the oil in the engine? Well, it’s pretty straightforward to tell if the oil is still fit for purpose just by looking at the condition a bit more on that later. First, it is better to understand why engine oil goes bad.
Does engine oil go bad?
In short, yes, engine oil goes bad. Over time engine oil in a bottle on the shelf degrades, and the properties and additives in the oil become redundant, rendering the oil useless without it even being in an engine.
When an engine oil degrades much quicker, it is exposed to carbon contaminates, moisture, and in some cases, fuel which is when it becomes less viscous. Engine oil is a thick fluid that doesn’t flow very quickly; when warm in a running engine, it flows more freely, properly lubricating the engine. Without proper lubrication, engine components will eventually fail. Engine oil that has become less dense will not lubricate engine components correctly. Equally, engine oil that is too thick that becomes like treacle will have a similar effect, although this doesn’t usually happen with oil sat for long periods.
How long does oil last in a car not driven?
In a car not driven, engine oil lasts about 12 months. It is possible that if the engine oil were new before the vehicle was parked for an extended period, it would last much longer, even up to its expiration date printed on the bottle. Which you may think is as long as five years; however, in an engine, the degradation process is much faster than in a sealed bottle. It is almost impossible to tell if the oil has degraded without using technology found in laboratories.
Most car manufacturers recommend that engine oil be changed around 8 – 10,000 miles or 6 – 12 months, depending on the type and amount of driving you do. Although the engine can last, if the car is not moved for 6 – 12 months, it is recommended that you replace the oil before using the vehicle again. Replacing the engine oil is suitable for vehicle maintenance and will prevent further issues later.
How can you tell if engine oil is no good?
There are some simple ways to tell if the engine oil is still good, the obvious being to look at it. Remove the dipstick, wipe it clean and recheck the level. If the oil on the dipstick is still a relatively clear brown color and has new oil viscosity, the engine oil is still in good condition. However, if the oil on the dipstick is dark brown/black and thick like treacle, the oil will need replacing.
The other issue that can happen when a car sits for some time is the oil will become low; this could be because of a minor oil leak. As the oil will have been exposed to moisture through the leak, replacing it rather than topping it back up will ensure you get rid of any poor-quality oil.
What happens if you drive a car with old oil?
The are several issues driving a car with old, degraded oil. Most important is that the oil can no longer do its job. The oil that no longer has lubricating properties will no longer stick and lubricate components that need it. Contamination and burnt carbon cause the oil to coagulate (thicken), and thick oil can no longer lubricate parts. Essentially the oil will be the wrong viscosity so it will not be passed around the engine efficiently, causing the filter to block, bearings, and pistons to dry out. It will result in engine seizure and failure.
Lastly, degraded oil loses its cooling ability to keep internal engine components at set temperature levels, burning in the process and giving off a pungent smell. Basically, driving a car with old oil that has not moved for more than 12 months could pose risks to the engine.
To answer the question of how long does oil last in a car not driven? It is approximately 6 to 12 months. If you check the condition of the oil by looking at it, you will be able to confirm if it has expired. It is likely no good if it no longer looks similar to new engine oil. The only thing you can do with bad oil in an engine is to replace it. Driving a car with old engine oil will cause problems and is not worth the risk of causing damage for an inexpensive oil change.