How to Break in a New Engine
Buying a new car is exciting. Nothing beats the new car smell and ease of maintenance that comes with a new engine.
If you’ve just bought a new car, you’re probably hoping that your new engine will last for 20 years, or at least until you want to upgrade. How you break in your new engine can affect the life and condition of your engine over time.
What does it mean to “break in” a new engine? “New engine break-in” means a procedure performed on a new or remanufactured engine to ensure that all components fit properly and function smoothly. During the break-in period, the engine’s moving parts, especially the piston rings, cylinder walls, camshafts, bearings, and other components, wear in a controlled manner to form tight, efficient seals.
Break-in typically involves operating the engine under various loads and speeds for a specific number of miles or period of time. Manufacturers often provide specific guidelines for this process.
The goal is to make engine parts bond and wear in a way that improves life and performance. Proper break-in will ensure your engine operates as designed, maintains good fuel economy, and reduces oil consumption and emissions over its useful life.
Tips for Breaking In a New Engine
Breaking in a new engine is very simple. Here are some general tips to help keep your engine running for the life of your vehicle:
1) Follow the manufacturer’s recommendations.
No one knows your vehicle better than the engineers who developed it. If the manufacturer specifies a break-in procedure in the owner’s manual, you should follow that procedure (even if it differs from this procedure). Many manufacturers have established engine break-in guidelines, such as: Vary engine speed, avoid full throttle, and keep below 4,000 rpm for the first 1,000 miles.
Modern vehicles store telemetry data in the ECU. If you need to bring your vehicle in for warranty repair, the technician will likely check your vehicle’s computer to see your operating speed, maximum throttle, and maximum RPM.
If you drive your vehicle hard before reaching the target break-in mileage, you may run into engine warranty issues.
2) Avoid redlining
As an engine breaks in, the seating and rotating components connect with each other. Small metal parts wear out during the first few thousand miles of running an engine. Once the engine is stable, wear will be minimal if you take good care of it.
You can actually do damage by running the engine at high speeds before breaking it in. This can damage the bearing surfaces, cylinder walls, or piston rings. This is especially true if you run the engine at high temperatures.
3) Avoid full throttle (at least at first)
For the same reasons you want to avoid the redline, you should avoid full throttle if possible. Full throttle puts more strain on the engine and stresses components that may not be fully broken in yet.
Engines that are not properly broken in can experience increased blow-by and oil consumption as they age. In extreme cases, you may even experience spinning bearings. If you have spinning bearings, your engine needs a bottom-end overhaul.
4) Be careful with your clutch
If your engine is new, chances are the rest of your car is new too. This means there are other components, such as the clutch, that should break in at up to 1,000 miles.
If your new car has a manual transmission, it’s totally normal to notice a slight smell of burnt clutch, even if you’ve been careful with the clutch while driving. This smell should mostly go away within the first few thousand miles.
5) Vary your engine speed (avoid cruise control)
Varying engine speed during break-in helps ensure the piston rings wear evenly. Cruise control does not put a lot of strain on the engine, but operating cruise control for extended periods during break-in can disrupt this process.
6) Avoid idling
For the same reasons you want to avoid cruise control, you should also avoid idling. When idling, the engine is running at a slow, single speed. You also want to put some stress on the engine.
Engines work best at their operating temperature when they are operating under a variety of loads. If you drive many kilometers with a new engine, you can gradually increase the maximum load on the engine.
7) Driving in the city
When driving around town, this is an easy way to naturally vary the load on the engine. Gentle acceleration and coasting are good for new engines in stop-and-go traffic and from traffic light to traffic light.