Is New Engine Break In Procedure Still Necessary?

I don't believe at all on the letting the engine idle or using remote start is putting more fuel in the engine vs normal driving and getting in the oil. The metered injectors are putting enough fuel in the cylinder needed for combustion and more fuel for higher rpm's so way less fuel at idle that is burned off when combustion is happening. So what is being said here is fuel at idle is washing down the cylinder and draining down to the oil. No way. Only way is if the engine rings are worn and your getting blow by then gas will get in the oil or you have a leaking injector dripping fuel in the cylinder when the motor is not running.

@Silverado4x4

Believe what you want. DI engines are a much different animal than previous port injected engines. The higher pressure fuel delivery with DI, especially when the engine is cold will leave liquid drops of fuel in the cylinders especially around the piston rings, liquid fuel does not burn, so it will work its way quicking into the crankcase.

Additional you need to understand the engine coolant temperature and oil warm up behavior of an engine that is just idling from cold start vs driving. See graph below. Cold Start Idle was for 15 minutes, Drive was 17 minutes. Even at 17 minutes of driving the engine oil was only around 175F even though the engine had hit 200F. This was semi rural driving with at best maybe 4 traffic lights and speeds typically between 35-45 MPH. The engine was not even 100% fully warmed up at 17 minutes of driving, usually these engines operate between 203-210F when fully warmed up. Ambient temperatures due influence warm up times, but we are still not out of the Winter temps in many areas. Many owners tend to use the Remote Start features more when the temperatures are colder to warm the cabin and clear the windows, I get it, sometimes you need to to this, but doing this on a regular/daily or multiple times a day basis is not a wise idea.

It also not all about the engine idle time as well, it is about getting the oil, not the engine, up to a high enough temperature to start to "cook" fuel out of the oil. Again, fuel contamination of the oil can be cumulative depending on the outside ambient temperature and how the vehicle is driven. The more short drives, the worse the problem gets.

Pull your dipstic, check the oil level and smell te towel used to wipe the dipstick for fuel. A number of reports about vehicles fresh off the dealer lot have fuel smell in the oil.

yes I think there is reason to alter driving habits with a new engine, even with modern engines. I would opt to drive it such that the rings will get a good wear pattern. This would be something like stop and go driving and/or varying rpm slightly for a few hundred miles. It doesn't have to be perfect. You won't trash your motor if you don't do this to perfection. The reality is that before you signed the papers 4 other people drove your car and likely floored it repeatedly. lol.

And the DI engine's propensity to put fuel into the oil, I recommend the first oil change quite early as well. I did mine at 1800 miles.

I had a 4runner that I bought off the lot and went on an off roading trip. I literally left with gear from dealer lot. Lots of highway miles and heavy acceleration to pass. High altitudes where the anemic 4runner engine stayed at 4.5K for minutes on end to keep 78 mph. No issues and a total violation of the owners manual break in procedure.

The owners manual describes the GM proscribed break in process, which is essentially not much.
Don't use cruise or drive at constant speed/rpm for the first 500 mi
Be gentle on brakes while the pads and rotors seat to each other
Don't tow for firt 500 miles.


Past that I would try to do a few full thermal cycles of getting the engine to full operating temp, then letting it cool all the way back down (which you will probably do anyway in 500 miles).
And maybe somewhere past 350 miles, give it a few higher RPM runs (but not Wide Open Throttle) to around 3500-4000 RPM.

WalleyeMikeIII said:

View attachment 451849

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2025 Corvette Owners Manual said:

For the first 322 km (200 mi):
• To break in new tires, drive at moderate speeds and avoid hard cornering.
•* New brake linings also need a break-in period. Avoid making hard stops. *This is recommended every time brake linings are replaced.

For the first 800 km (500 mi):
• Avoid full throttle starts and abrupt stops.
• Do not exceed 4000 rpm.
• Avoid driving at any one constant speed, fast or slow, including the use of cruise control.
• Avoid downshifting to brake or slow the vehicle when the engine speed will exceed 4000 rpm.
•* Do not let the engine labor. Never lug the engine. *This rule applies at all times, not just during the break-in period.

For the first 2 414 km (1,500 mi):
• Do not participate in track events, sport driving schools, or similar activities.
• Check engine oil with every refueling, and add if necessary. Oil and fuel consumption may be higher than normal.

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Pity that break-in procedures do not include disabling Engine Confusion / DFM.