how to engine break-in

Engine Break-In How To | Do It Right The First Time!

So you've spent a good amount of money building up you motor. You've carefully planned the entire build, from bearings to pistons, and crank to cams. No corners were cut in your pursuit of power, and you've got the receipts to prove it. But before you turn the key for the first time, there are a few important things to check, and neglecting them could be the worst decision you've ever made. Below we'll go over the process of the proper engine break-in procedure.

  • Safety First
  • Priming The Engine
  • Proper RPM's
  • Run Times
  • Oil Type and Oil Change Intervals

Here at MAPerformance, we've built hundreds of high-output engines in the many years we've been in business. We have a large clean room where we build all of our performance Evo and Subaru shortblocks, and our dedicated team of engine builders know exactly what it takes to assemble an engine for reliability and performance! Feel free to give us a call with any questions you may have, or click here to download a copy of our engine break-in procedure!

Safety First

Thoroughly inspect all moving parts you've touched during the removal of your old engine or installation of the new mill. Check coolant, gear oil (or ATF), and engine break-in oil for proper levels. We recommend AMSOILD SAE30 Break-In Oil for initial start up and break in. Lastly, before you fire it up for the first time, ensure the parking brake is set, and the transmission is in neutral. It's also a good idea to chock the wheels.

Priming the Engine

Priming the engine is as easy as removing the crankshaft position sensor and cranking the engine until the oil light shuts off. It's also a good idea to remove the fuel pump fuse. if you don't have an oil pressure light on your dash, purchase an aftermarket gauge so you can keep an eye on oil pressure. Ensure you're making pressure while turning the engine with the CPS unplugged. If all is good, connect the CPS or Fuel Pump Fuse, and start the car.

Proper RPM's and Engine Run Times

After the first start, let the engine run for 20 minutes at varying speeds between 2000 and 3000rpm. It is critical to vary the RPM's for proper camshaft break-in and to ensure the piston rings and moving components are properly broke-in. After the first 20 minutes, inspect for oil, coolant, or fuel leaks. If all is good, take it on the road. Driving periods vary based on application, but no less than 30 miles is recommended. Head off to a low traffic area, where you can do long pulls at low load followed by engine braking back down to idle. This process is called "Vacuum Pulls" and helps seat the piston rings. Repeat no more than 50 miles and avoid open throttle and full boost scenarios. Watch your gauges like a hawk, and make any adjustments to your AFR's at this point.

After the initial break in period, you'll change your oil and then repeat the process until you've hit the 500 mile mark. After this, your engine will be fully broke-in.

Oil Change Intervals

Initial start up requires SAE 30 break-in oil and a new oil filter. If you dont have any SAE 30, conventional oil is fine. This oil will be in the engine from initial startup to the 50 mile mark. Change the oil at 50 miles, and again fill with SAE30 break-in oil or conventional oil type and run using the process outlined about for another 450 miles. At 500 miles, you'll change the oil once again with conventional oil and a new filter. The last oil change you'll make before completing the engine break-in procedure will be at 1500 miles, at which point will be conventional or synthetic oil and a new filter. From here on out, the typical 3000 mile interval is recommended.


An engine is the heart of any build. It's not the turbo, the intake, the clutch, or any other aftermarket part. Without an engine, you have a fancy garage decoration. Protect your investment by following the proper engine break-in procedure and you'll be able to enjoy your investment for years to come!