GM 5.0/5.7L pre-1996 Engine break-in procedures:

  1. Use of AC/Delco engine oil supplement is recommended for start-up. **
  2. Prime engine for at least two minutes with an air/oiler system of the engine's oil pump diven by a drill & adapter or other external source (Do Not use starter to rotate engine).
  3. Complete all necessary "tune-up" procedures including setting ignition timing prior to starting the engine for the first time. (Excessive "cranking" of new engine with starter is not recommended).
  4. GM recommends a 30 minute "run-in" of the engine as either a short road test of running at high idle (1200 rpm) to break-in the camshaft. Check for leaks, watch oil pressure and engine coolant temperature, and then change the engine oil and filter arter initial "run-in". If road testing, drive in both city and highway conditions if possible, but do not exceed 90kph.
  5. A follow-up oil and filter change after an additional 500-1000 km should also be made before returning to the regular engine maintenance schedule.
** marine engines should use genuine Mercruiser engine oil or HD30 engine oil (10W-30 is not recommended for pre-roller cam engines).
Sources: ©AERA 2006, permission of General Motors Corporation, Service Operations