4 cyl instructions:
1. in order for the cleaner to be effective, the engine must be warm.
2. Disconnect negative battery cable.
3. Remove spark plugs.
4. Rotate engine crankshaft until notch in crank pulley is at 3 o'clock (90° after top dead center) position. This will position all of the pistons midway in their bores.
5. Pour 3 ounces of GM Piston and Ring Cleaner (P/N 12378549 12 ounce bottle) into each cylinder through the spark plug hole.
6. Cover the cylinder head and spark plug holes to prevent debris from getting into the combustion chamber and to prevent excess evaporation of the cleaner.
7. Allow the engine cleaner to soak for a minimum of 2 hours.
After the minimum 2-hour soak, there may be some cleaner left in the combustion chambers. Do not start the engine until all of the cleaner has been removed from the combustion chamber or severe engine damage may occur.
8. After the minimum 2-hour soak, remove the remaining cleaner from the combustion chambers by placing shop towels over all of the spark plug holes and cranking the engine through a few revolutions.
9. Install the spark plugs and spark plug wires.
10. Start the engine and run only enough to reach normal operating temperature.
11. Drain the engine oil and remove oil filter.
