The Need for New Engine Break-In Is Not a Myth Says This Expert, After Looking at His Daughter's 2023 Toyota Corolla

According to a recent The Motor Oil Geek YouTube channel episode, the host’s daughter’s Made-in-Japan 2023 Corolla is due for an oil change at just over 10,000 miles by the dealership as part of their free Toyota Care service.

However, the car’s oil had actually been changed much earlier than that by the host because of his belief that a new vehicle’s first oil change should come much sooner than the recommended 10,000 miles.

Related article: Why You Cannot Trust Your Car’s Maintenance Recommendations

What’s the story behind this?

Are Modern Car Engines Broken in at the Factory and Therefore Do Not Have a Break-In Period?

A new engine break-in period makes sense because we’ve known in the past that when it comes to a new engine, the cylinder walls and the piston rings are physically mating to each other for a good fit.

However, you will find a lot of comments and arguments online about breaking in an engine as a thing of the past, and that the modern-day car engine is already broken in at the factory.

However, do we really know that the factory in Japan (or anywhere else for that matter) has actually broken in the engine before sending it off to the dealerships? Or do we really still need to treat that new car to a break-in period and care?

Let’s let science do the deciding for you is the recommendation of Lake Speed, Jr.―a tribologist who specializes in understanding how friction, wear, and lubrication interact with each other in car engines.

“What I see on the internet is a ton of speculation and not a lot of science,” says the host as he puts the engine break-in question to the test using his daughter’s new car to see how oil samples from her engine compare between it’s first and second oil change.

Follow along with the host in this short 10-minute video where science rules.

Please Note: If you want to skip the video, below the video is a summary of what Lake Speed found and discussion of what you need to know when it comes to your new car engine.

New Engine Break-In: Truth Or Myth?

Oil Analysis Results Summary

• Iron, Aluminum, and Copper are the key wear metals you should monitor in this test between oil changes.
• It is the wear rate change you are looking for when comparing the wear metals between samples.
• If the wear rate between oil samples remains the same, the engine has already been broken in before being sold; If the wear rate changes (decreases) between samples then break-in wear is occurring.
• From the earliest to the latest samples recovered, there was a clear decrease in the wear rate according to oil analysis tabulating the number and amount of metals detected in the oil samples.
• Conclusion: The engine was not broken in at the factory.

Why Isn’t Break-In Motor Oil Used in New Cars Anymore?

There are two interesting answers to this question, and it has to do with how cars are provided to the public.

1. Blame Car Leasing Bad Habits―Before the 1990’s most car owners bought their cars; After the 1990’s more cars were leased as opposed to being bought new. The crux of this matter is that car “owners” who lease their cars tend not to maintain their leased vehicles as well as they would have if they had invested in buying a car over leasing it.

When a car was provided new at a dealership the engine had break-in oil already in the car that possessed very little detergent and dispersants making it a bad oil for driving thousands of miles before switching to a non-break-in oil. Without switching motor oil types after the break-in period due to poor maintenance, the engine would sludge-up from the neglect. Since the leased car would still be under warranty, the manufacturer would have to foot the bill for sludge induced repairs.

2. Blame the EPA―The EPA is not interested in how cars work or the details of why decisions are made such as no longer providing break-in oil when all new cars need it. Rather, the EPA is focused on fuel economy.

According to the Lake Speed, Jr. the EPA shows up at a dealership, buys a new car and then tests it for its fuel economy. If the car does not meet the latest fuel economy demands, the manufacturers get dinged for it. As it happens, break-in oil worsens fuel economy measurements. Hence, another reason why auto manufacturers no longer provide new cars with their initial break-in oil like they used to.

In other words, there is a big financial incentive for auto manufacturers to do away with the break-in oil pretreatment and just hand over cars with motor oil that will carry the vehicle just beyond its warranty period.

Should I Add Break-In Oil to My New Car?

Talking to a machinist about rebuilt engines, his recommendation over the years through experience is that you really need to use break-in oil for at least the first 500 miles and then switch over to a full synthetic oil with all of its modern additives to prolong the life of any engine.

His comment was that many people would be surprised at how much initial wear takes place on a new or rebuilt engine as the piston rings wear-into the cylinder walls for that perfect fit of a thin film of lubricating oil.

However, we were talking more about rebuilt engines.

When it comes to a new car there is the risk of voiding your warranty doing anything to the car that the manufacturer does not explicitly recommend. In the case of adding break-in oil on your own, there is a chance that the manufacturer might surmise that using a professional break-in oil was the cause of your car’s problems, leaving you footing the bill.

Your best bet is to make more frequent oil changes than the manufacturer recommended for at least the first few thousand miles and then stick to a schedule on a regular basis how often you change your motor oil based on your car’s driving conditions.

For additional motor oil related articles, here are three for your consideration:

• Important Oil Filter Trick for Longer Engine Life
• What Happens When Your Car’s Oil Filter Gets Clogged
• Oil Change Failures: Expect the Unexpected

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: Toyota’s New 0W-8 Motor Oil is Too Thin?

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