What Happens When You Shake Old and New Motor Oil

In an earlier article we learned about whether motor oil can go bad on the shelf and whether or not it is ok to still use.

As a result of the findings about aging motor oil posted on The Motor Oil Geek YouTube channel, viewers wanted to know if old oil can be shaken to bring additives that have settled to the bottom of the container to “refresh” the oil, as well as whether new oil should be shaken before pouring into your car’s engine.

Today, we are going to find out whether shaking does make a difference and whether it is an advisable practice when changing your car’s oil.

Related article: Is the Cheaper Costco Kirkland Oil Miserly on the Additives Your Car’s Engine Needs?

The Problem with Old Motor Oil

As we’ve learned, yes, motor oil can indeed go bad with age. This is due to exposure of the oil to the oxidizing properties of oxygen, prolonged exposure to heat, and the seeping in of contaminants and moisture occurring over time.

Degradation of oil results in a loss of viscosity, which is crucial for proper lubrication in the engine. Furthermore, the additives used in motor oil play an important role in improving motor oil lubricating and heat-resistance cooling properties; therefore, additive reduction through degradation can cause motor oil to lose its effectiveness in protecting the engine from wear and corrosion over time.

Storage conditions can also impact the shelf life of motor oil. Exposure to extreme temperatures, moisture, and sunlight can accelerate the degradation process.

Manufacturers typically recommend using motor oil within a certain period, usually indicated by a "best before" date printed on the container. It's a good idea to adhere to these recommendations to ensure optimal engine performance and longevity.

Best Way to Store Motor Oil

However, if there is good sale on a brand of motor oil recommended for your car, the following tips will help you preserve your motor oil to last its longest on the shelf:

1. Follow the Manufacturer Recommendations: First and foremost, look for any information from the manufacturer and follow their recommendations. If no information is printed on the oil can or plastic jug, look for a contact number to call for specific storage instructions.
2. Check for Leaks: Before storing your motor oil, be sure to inspect the containers for any leaks or damage. Return the oil if you find the container has been compromised.
3. Organize and Label: Keep your motor oil storage area organized and clearly labeled to easily identify different types of oil and their respective grades as well their dates of purchase and of expiration clearly visible.
4. Choose a Cool, Dry Location: Store motor oil in a cool, dry place away from direct sunlight and extreme temperatures. Do not store it in the basement, which is often damp. Also, avoid storing your oil beside a furnace or other sources of high heat.
5. Keep Containers Sealed: Make sure the containers remain tightly sealed during storage. Do not open a bottle every now and then for whatever reason. An opened bottle or broken seal will allow air and moisture to enter and prematurely age your motor oil.
6. Store Your Oil Away from Other Chemicals: Store your motor oil separately from cleaning products, solvents, or other automotive fluids.

The Motor Oil Geek’s Findings Summary

So, back to the question of whether or not shaking old or new motor oil makes any difference, The Motor Oil Geek and his cohosts put samples of both old and new oil under a battery of tests that involved:

1. Both shaking and not shaking old, stored motor and gear oil and sending it to a lab for oil additive analysis and foam formation testing.
2. Both shaking and not shaking new motor and gear oil and sending it to the same lab for oil additive analysis and foam formation.
3. Comparing the oil analysis results against each other looking for significant differences or improvements.

For all oil samples tested:

1. Shaking old oil does not physically appear to dislodge or resuspend any additives that have settled to the bottom of their containers.
2. Old oil samples possessed moisture contamination and higher oxidation levels indicating oil degradation occurred meaning that the additives are chemically degraded regardless of shaking or not shaking the old oil samples.
3. Both old gear oil and motor oil samples show excessive foam formation (shaken or not) compared to modern new oil (shaken or not).

The Ending Conclusion of Whether Motor Oil Needs to Be Shaken Before Use

• Old motor oil and gear oil are guaranteed to go bad, do not use either.
• Even if the old motor oil and gear oil did not go bad you should not use it in a modern car due to new oil formulations are vastly improved toward protecting your car’s engine.
• Shaking old or new oil does not improve or harm either type of oil; thus, there is no benefit (or harm) to shaking your motor oil (either old or new) in its container before adding it to your car during an oil change.

For more details about how the tests were done and what the results look like, here is the video posted below that is well worth watching:

Lab Results: Does Motor Oil Need to Be Shaken Before Use?

For additional articles on your car’s engine oil, here are a few for your consideration:

• Oil Stop Leak Product Warning for Car Owners
• Avoid the Diagnosis Trap When Smelling Burning Oil
• A Simple Test to Avoid an Oil Leak Scam on Your Toyota

Timothy Boyer is an automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on  “Zen and the Art of DIY Car Repair” website, the Zen Mechanic blog and on Twitter at @TimBoyerWrites  and Facebook for daily news and topics related to new and used cars and trucks.

COMING UP NEXT: The Bad Idea to Buy Used Lexus Model

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