It's time for an oil change, and you've stumbled upon a quart of oil in your garage, either from your car's last service or maybe it's's been there for years! Is it safe to use in your vehicle? Can oil go bad? We've done the research, and these are the facts about the shelf life of motor oil.
Engine oil has an expiration date. An unopened bottle of motor oil is typically good for five years. For previously opened oil containers, it's best to use oil within one year. Several factors contribute to whether or not engine oil goes bad, so before pouring oil into your vehicle, please consider:
- Oil additives
- Manufactured date
- Unopened or opened container
- Storage location and conditions
It's safe to say that all modern engine oils have roughly the same shelf life, assuming proper storage. All of the previously mentioned factors contribute to the longevity of motor oil and should be considered before using it in your car. Keep reading as we dig deeper to discuss what to look for when inspecting engine oil, and how these factors affect your oil.
How Can You Tell If Unused Motor Oil Is Bad?
Other than the date, there are several indicators that engine oil is bad. Don't count on these though, especially if you don't have enough experience with what good engine oil looks and feels like.
Motor oil should be light brown and easy to see through. If you notice your oil is cloudy or darker in color, it's's most likely either been heavily oxidized or contaminated and should be either recycled or properly disposed of.
Good oil is thin in consistency and should feel smooth and slippery between your fingers. If your oil is thick, rough, or sticky, then it has likely gone bad, most likely due to improper storage, and should not be used.
If motor oil has been sitting for too long, sediment deposits can collect at the bottom of the container. These deposits come from additives in the oil used to maintain the oil's recommended viscosity or thickness. Unfortunately, there is no way to dissolve sediment deposits back into the oil, so you should not use it.
Where Is The Expiration Date On Motor Oil?
Most motor oil will not have an explicit expiration date on the bottle, but you should check to be sure. If you locate an expiration date and the date has passed, then you shouldn't use the expired oil in your car.
If you can't find an expiration date on the bottle, you should check for a manufactured date. This date is commonly printed directly on the bottle. The manufactured date indicates when the oil was made and thus how old it is now. Determine the maximum shelf life of any oil brand by contacting the manufacturer directly, either via website, email, or telephone.
How To Store Open Motor Oil?
To make your engine oil last longer, make sure to store it properly. Here's what you should pay attention to -
Open containers of motor oil need to be kept in a dry location to avoid contamination with moisture. Each time you open a bottle of engine oil, you let in air and water vapor. The air will start the oxidation process, and the water vapor can condense on the sides of the container and mix with the oil. The lower the level of oil in the container, the more surface area there is for condensation to occur. Excess water in your oil will lower its viscosity, making it less effective at lubricating your engine.
All motor oils, either opened or unopened, need to be stored within a temperature range between 32°F - 85°F and should be kept at a consistent temperature during storage if possible. Extreme temperatures and temperature fluctuations can cause your oil to break down and will alter the viscosity of your oil; therefore, it won't be as effective at lubricating your car's engine.
It is a good idea to keep your new motor oil in its original container even after you've opened it. Transferring new oil to another container could expose it to contaminants such as dust and dirt, which will reduce its shelf life and could hinder its performance in your car's engine.
Does Oil Go Bad Sitting In An Engine?
Unfortunately, yes, motor oil can go bad while sitting stagnant in your car's engine. The oil in your vehicle is subject to all of the factors we've just discussed that affect the storage of an open container of oil—both the temperature range of your stored car and the age of the oil in the car's engine matter.
If you run your car regularly, then this isn't something that you need to worry about outside of regular service. However, if you plan on storing your car for more than a month, then you should drain the oil completely before you store the vehicle. Draining will prevent oil sediments from building up in your car's engine, which can be difficult and costly to remove.
One notable difference between storing an open container of oil and the oil sitting in an engine is the potential for sediment build-up. The oil in your engine is much dirtier due to soot, burning oil, and small bits of metal from the mechanical movements of your engine. Letting your car sit without running for an extended period will increase the amount of sediment build-up in your car's engine and could potentially cause irreversible engine damage.
How To Dispose Of Expired Motor Oil?
If you've decided that you can't use the expired oil you've found, what should you do with it? Unfortunately, you can't toss it in the garbage. Motor oil is considered highly toxic to the environment and should be disposed of properly.
Many service stations will collect motor oil for recycling and disposal. You can search the web for local oil recycling and disposal centers near you. If you're not going to recycle or dispose of the oil right away, you should make sure it's's appropriately stored in the meantime.
Store expired (or bad) oil in a clean, leak-proof container with a tight seal. It should be stored out of reach of pets and children, and labeled clearly. A clean container is essential because if the engine oil is contaminated with other chemicals or foreign substances, it cannot be re-refined and recycled and must be disposed of.
Motor oil won't sour or mold, but it will degrade, oxidize, and become potentially harmful for your car. When deciding whether or not to use old motor oil, you should ask these four questions:
- How old is it?
- How was it stored?
- Has it been opened?
- How does it look and feel?
If you're unsure of any of the answers to these questions or the oil has expired, it's best not to use it. In the end, if your engine oil isn't too old, has been appropriately stored, feels smooth, and looks clear and free of deposits, then you can be confident that you're using good quality oil in your car. For more helpful engine oil tips, check out our other blogs: