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Does Motor Oil Expire? (How To Tell + FAQs)

October 15, 2021

Imagine this:
Your car needs an oil top-up, and there’s an unopened container of motor oil in your garage that’s been lying around for a while. 

Can you use it?
Does motor oil expire? 
If so, how long does it last? 

In this article, we’ll try to answer those questions and look at ways to tell if your motor oil has expired. We’ll also discuss some related queries about motor oil expiry and disposal. 

This Article Contains:

Let’s get started!

Does Motor Oil Expire? 

Yes, it does. 

But determining whether it has gone bad is not as simple as relying on the expiration dates labeled on the oil container. 

While motor oil (traditional mineral oil and synthetic oil) is believed to stay stable under optimal conditions, it’s bound to lose its efficiency after a few years.

In addition to its expiry date, factors like extreme temperature changes, oxidation, and the role of synthetic additives in your oil should be kept in mind. How you store it also affects how soon it may expire. 

There are several ways to ensure that it stays good for long, but you first need to know how long it lasts. 

How Long Does Motor Oil Last?

How long your motor oil lasts will depend on the type of oil you’re using and how you store it

Conventional oil (also known as mineral oil) is often not as refined and won’t last long. 

On the other hand, synthetic oil and synthetic blend oil contain synthetic additives that perform better under high temperatures. This means that they will also last longer than any conventional motor oil (where the base oil is made up of crude oil and is therefore not very stable).

The oil life also depends on how you store these oils. 
Let’s take a closer look:

Unopened Motor Oil

Generally, unopened motor oil (both conventional and synthetic blend) will last for an extended time as it is in a sealed container.

Motor oil stays good in the oil bottle until its expiry date when unopened. This will give you about 2-5 years before unused oil becomes unfit for consumption. 

Unless you need to use the oil, do not open the oil bottle at all. 
Keep in mind, though, fresh oil will degrade over time and lose its oil additives properties, impacting the oil life. 

Half-Opened Motor Oil

While your motor oil bottle will indicate an oil life of about 2-5 years, this is mainly for unused oil. 

Once you open the bottle of oil, it will start losing its effectiveness. 
Half-opened bottles of fresh oil are best used within one year of opening. 

Irrespective of whether you’re using synthetic oil or conventional oil, dirt and moisture will contaminate the oil over time once the bottle has been opened. This can degrade the efficiency of the oil as a lubricant and the overall fuel efficiency of the car’s engine.

A half-used bottle of engine oil is also vulnerable to oxidation, which can increase the viscosity of the oil. Oxidation will in turn, result in the formation of sludge and sediments. 

Oil Left In The Engine

If you drive your car regularly and have a set oil change interval, you don’t have to worry about motor oil going bad while in the engine. 

However, make sure you completely drain the old oil every time you store your car for more than a month

Oil that is stagnant in the engine will suffer a similar fate to that stored in a half-opened bottle. It’s likely to oxidize and lead to the formation of sediments at the bottom. Oxidation may also lead to the formation of acids in the engine, which may cause corrosion of certain parts. 

So how do you tell if your motor oil has expired? 

4 Ways To Check If Your Motor Oil Has Expired

Motor oil that has gone bad can be tricky to spot, but these signs will give you a good idea that it’s no longer good: 

1. Expiry Date

The expiry date of your engine oil is a clear way to identify how long it will last. 

Most conventional oil brands will have a shelf life of about 5 years. 
Synthetic oil and synthetic blend oil will last about 7-8 years, and maybe even longer.

If you cannot find the expiry date, make sure you use up any half-opened or unopened motor oil bottles within 2-5 years of the manufacturing date. And if your unused oil looks good but has surpassed the expiry date, it is best to dispose of it. 

2. The Color Of The Oil

Good quality engine oil features an amber hue. 

If you use a dipstick to check your oil level, and notice that your oil appears very dark and muddy, it has probably oxidized. It could also have been contaminated with dirt and moisture from the engine. Half-opened bottles of regular oil also often come in contact with dust and darken. 

In all of these cases, it has likely gone bad and is unfit to use.

3. Appearance

Both conventional and synthetic motor oil is clear and translucent. 

It should not appear milky or hazy. There should also be no separation of additives or dust particles in the oil, and it should appear flowy and stable. 

If you spot any of the mentioned changes, your oil bottle has probably expired.

4. Consistency

Motor oil is supposed to be thin and smooth and fairly fluid in nature. 

If it appears too solid or thick or appears to have gained a slime-like consistency, it has probably expired due to moisture and lead to sludge formation. 

Now that we have that out of the way, let’s explore a few related queries about motor oil’s shelf life.

4 FAQs About Motor Oil 

Let’s have a look at the most common questions and their answers when it comes to motor oil expiration dates.

1. Does Synthetic Oil Last Longer Than Conventional Oil?

Yes, it does. 

Synthetic oil consists of base oil and oil additives and is carefully designed to withstand the high temperatures that car engines typically reach. Modern engine oils are formulated to require fewer oil filter changes and be more resistant to oil pressure. 

As a result, it can stay good for longer while in the container. And since it is not made up of crude oil like mineral oil, synthetic motor oil will have a better oil viscosity and be more fluid. 

Note: Gear oil and motor oil aren’t interchangeable. They’re two different sets of oil for different uses.

2. What Can I Do To Increase The Shelf Life Of My Motor Oil?

The following things can help you get the maximum shelf life out of your motor oil bottle. 

3. Can I Use Expired Motor Oil? 

Old, expired oil may not be as efficient as fresh oil, and it may damage your engine parts. Plus, it can lead to problems like acid buildup, inevitably resulting in corrosion. 

It is best to dispose of any expired oil to prevent further damage to your engine parts and the car’s engine fuel performance.

4. How Do I Dispose Of Expired Oil? 

Motor oil is highly toxic and cannot be disposed of in the garbage or sink like regular oil. You’ll need to collect the old oil in a clean plastic container. 

You can either drop it off at a local waste collection outlet or contact an auto workshop to see if they collect it.

If you don’t plan on making a trip, store the old oil in a tightly sealed container and keep it away from the reach of children or pets. Don’t be hasty with your motor oil disposal; you might be in for a fine!

Final Thoughts

Whether you purchase a bottle of conventional oil or synthetic motor oil, it’s bound to expire at a certain point. 

Expired motor oil is often very acidic and can cause severe damage to a car’s engine performance. Fortunately, we can always replace it and get a new bottle for a fairly low price. Remember to dispose of it responsibly, and you’re good to go.

If you need help replacing your motor oil and give your car much deserved TLC, you can always contact RepairSmith!

With RepairSmith, you’ll get competitive pricing and upfront cost estimates. Reach out to them for easy, hassle-free mobile car repairs and maintenance!