Do New Cars Still Need An Engine Break-In Period, Or Is It Just A Myth?

From Hercules to Bigfoot, the world loves a myth, and autodom has its fair share. We've even compiled some of the dumbest car myths that readers have heard. Spoiler alert: a car engine's break-in period is not on that list. That's good, because it's not really a myth at all.

A break-in period — not to be confused with where your car is most likely to be stolen — refers to the time it takes for an engine's internal organs to get comfortable working together. Like leather boots molding to your feet, piston rings and cylinder walls rub against one another as the engine cycles. That friction causes wear, which creates debris that turns up in the oil over the lifetime of the car. That's why enthusiasts and technicians may send samples to an oil analysis lab to help monitor engine health, and make sure wear is within accepted tolerances.

The myth at hand here is whether modern car engines are broken-in at the factory, such that this initial bit of wear is of no concern as you take your shiny toy off the dealer lot for the first time. The truth is, engines may be tested for defects, but that's not the same thing. And some manufacturers do still include guidelines for safely breaking in your new car.

Merriam-Webster defines tribology as "a study that deals with the design, friction, wear, and lubrication of interacting surfaces in relative motion (as in bearings or gears)." Lake Speed, Jr. is the son of NASCAR veteran Lake Speed, and a real-life tribologist. To spare us the hard work, he's put together a great YouTube video with comparative oil change trend analysis, using science to see whether the engine is in fact breaking in. 

Speed also touches on why he did an early oil change, as well as two reasons — leasing cars and fuel economy standards — why manufacturers have extended their oil change interval recommendations.

How about hybrids and EVs? Hybrids have internal combustion engines, and may come with their own specifications for engine break-in. As for EVs, new parts like brakes and tires can take some time to wear in. Tires will go through heat cycles and shed new tread that may have lubricant remnants from the factory in the first 500 to 1,000 miles. Likewise, it can take around 500 miles for the brake pads to settle into their friction surfaces.

Perhaps the biggest factor that contributes to the no-engine-break-in myth is the variation in how — or whether — automakers define and specify break-in recommendations. 

BMW, for example, says, "Doing an engine break-in used to be a standard procedure with new cars. And it's still the case that you should avoid running the engine at high RPM for the first 1,300 miles."

Ford is also unequivocal in the 2025 Mustang Owner's Manual: "Your vehicle requires a break-in period. Drive your new vehicle at least 100 mi (160 km) before performing extended wide open throttle maneuvers and at least 1,000 mi (1,600 km) before operating your vehicle at high speeds or track conditions."

Subaru indicates a break-in period for its 2025 Outback. A search of the 2025 Mazda CX-30 manual revealed no mention of a break-in period, but precautions were suggested in 2021. Picked up a new Chevrolet C8 Corvette? There's a video about the 2025 Corvette break-in procedure on Chevrolet's YouTube channel — and the tachometer changes after the car's broken in.

Unless you're driving a Bugatti, which provides engine break-in on a 250-mile drive before delivery, your best bet is to ask your dealer, and check the owner's manual before you go redlining off the lot.