Does Engine Oil Expire? [Here’s What You Need To Know!]

Engine oil reduces friction inside the engine of cars and other motor vehicles.

It acts as a lubricant when you put it inside of them, and it helps minimize mechanical wear. 

But if it’s been sitting on a shelf in your garage for years or if you haven’t turned your engine on in a long time, you may be wondering if your engine oil has expired (if that even is such a thing).

Leaving engine oil on the shelf for too long could make it go bad. They’ve got a shelf life of around 5 years if you don’t open the bottle. If it’s opened, the shelf life decreases by quite a bit. An open bottle might last 6 months if it’s not left in the sun. 

Most engine oils use a variety of hydrocarbons to produce their effects. Unfortunately, hydrocarbon chains are sensitive to temperature and light. 

That’s why they’ll break down if you’ve put them in the sun. Warming them up also decreases their useful lifespan as well. 

Does Engine Oil Have an Expiration?

Modern production techniques infuse additives to change the properties of the final product. Some of them aim to extend the useful lifespan of engine oil by stabilizing their bonds. 

Technically, oil has an unlimited shelf life as long as it’s kept in optimal conditions. 

Few of us can store it somewhere ideal, though. So, it’s going to lose some of its efficacy after it’s been on the shelf for a couple of years. 

Pay attention to the bottle’s expiration date when you’re storing it. That should let you know when it’s expected to expire. 

However, you can prolong the oil’s lifespan beyond its expiration date by storing it well. 

Make sure it’s somewhere that’s not going to experience large temperature changes. 

You should try to keep it in a place that’s not exposed to the sun, too. Oxidation is one of the biggest factors affecting oil shelf life. 

Generally, conventional oil will have a shorter lifespan than synthetic. 

It hasn’t been refined as much, so it breaks down quicker. They’ve never had additives mixed into them, either. 

An unopened bottle of engine oil has a lifespan of around 2-5 years, depending on its quality. Keeping the bottle sealed can prevent it from breaking down too fast if you’d like to use it later. 

After you’ve opened the bottle, its lifespan decreases substantially. An open bottle of engine oil will last for less than a year. 

Make sure you’ve used it all by the time a year passes. Otherwise, the rest will go bad. 

Opening the bottle lets oxygen enter the container, even with the top on. Oxygen reacts with the hydrocarbon bonds, present within the oil. 

Over time, this lowers the oil’s viscosity, rendering it ineffective. 

If you’ve put oil in the engine, it should last a while. 

Driving the car prevents the oil from stagnating. Don’t let the car sit for longer than a month without draining its oil, though. Engine oil has a chance to oxidize if the engine isn’t moving it around often enough. 

Does Synthetic Oil Expire?

Synthetic oil differs from conventional oil in a couple of ways. These differences improve the oil’s characteristics and prolong its lifespan. Engineers put additives into the oil as part of its production process. 

Additives control some of its properties to enhance its performance in the engine. 

Some of them work by neutralizing oxygen before it oxidizes the oil. Other additives help control the oil’s viscosity, preventing it from getting too thin. 

That doesn’t mean synthetic oil lasts forever, though. You can expect it to outlast conventional oil, given the same conditions. But, it still has a shelf life if you look at the bottle. 

Another reason why it’ll last longer is the length of its hydrocarbon chains. Refining synthetic oil removes most of the shorter chains. 

So, the only ones left after refinement are relatively long. 

Long hydrocarbon chains are stronger and resist oxidation more effectively. 

How to Know When Your Engine Oil Is Expired?

What happens after the oil has passed its expiration date? There are a couple of ways you’re able to check whether your engine’s oil has expired. 

The simplest way to tell is by looking at the expiration date on the bottle. 

Most of the time, you’ll find a date somewhere on the bottom of it. Conventional oil typically has a stable shelf life of around 5 years if it’s unopened. 

Synthetic oil lasts for up to 8 years as long as it’s never opened. Take a look at the expiration date on your bottle if you’re not sure how long yours should last. 

Another easy way to tell whether your oil has expired is its color. 

Your oil should have an amber tone if you look at it under bright light. Try checking the dipstick to see what color your oil is. 

Expire oil has a much darker hue to it. So, if your oil looks dark, it’s time for a replacement. The color darkens as a result of the oxidation process. 

Fresh out of the bottle, oil looks almost translucent. You shouldn’t see particles floating around inside of it. 

Look at yours under a bright light to see if you notice anything in it. If you can see anything, you should replace your engine’s oil.

Viscosity describes how thick an oil is and how easily it flows. 

Fresh oil should flow relatively freely, without clumping. Aged oil becomes more viscous, turning into sludge. 

If your oil looks like sludge, it’s time to replace it. 

What Happens If You Use Expired Motor Oil

Using expired oil could damage the engine’s internal components if you’re not careful. Oil dampens friction when the engine’s components move around.

Expired oil doesn’t reduce friction as well, and it can lead to overheating. 

As a matter of fact, you could blow the whole engine if it doesn’t have enough oil. 

You may be able to drive a short distance if you’ve got expired oil in the engine. But, you shouldn’t drive too far without getting an oil change.

Fresh oil also prevents engine wear from occurring too quickly. So, if you’d like to prolong your car’s lifespan, always use good oil. 

How to Extend the Shelf Life of Engine Oil

You can make sure your engine oil lasts as long as possible by storing it in the right conditions. 

Temperature changes will cause the bonds to break down faster than usual.

So, keep oil somewhere that has a stable temp. 

Also, don’t let it sit in bright light. Ultraviolet radiation reacts with hydrocarbon bonds, weakening them over time. Leaving oil in the sun would decrease its shelf life by quite a bit.

Never open a bottle of engine oil if you’re not going to use it right away. The moment you’ve opened the bottle, you’ve decreased its lifespan substantially. 

Try to store the bottle in a place that’s cool and shady. It should also have low levels of humidity to prevent moisture accumulation. 

As long as you’ve done all this, your oil should last a while. You could still use synthetic oil after it’s been on the shelf for 8 years, as long as you store it well. 

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