Recently I've had a few people ask about engine break in. This is a touchy subject as everyone believes they know the right way. Here is what we recommend:

Check and fill all your fluids. We highly recommend Valvoline VR1 10W30 for stock to 400whp rebuilds, and 20W-50 for anything over 400whp. Start the car and let it run for about 30 minutes. Be sure to check for leaks. If there are any leaks, stop the car, fix them and start over. Watch the temp gauge, make sure the fans turn on at an appropriate time/temperature. After 30 minutes turn it off an let it cool off. Once it is safe to do so check your coolant level and change the oil and filter. Now drive 100 miles. Be as gentle or as hard as you want. Personally I prefer hard as I usually do this part on the dyno. After 100 miles change the oil and filter. Now drive 1000 more miles and change the oil and filter again. Then 2000 more miles and change the oil and filter again. At this point you’ll have a little over 3000 miles on your new motor and you can change to a synthetic oil if you want. Personally I stay with the conventional and just change it more often (about 2000 mile intervals instead of 3000)

Aaron Bunch

ATS Racing and Exotics