Tinstaafl fair point - but practically if you want 125 knots you may have a higher setting low level, and renters don't seem to lean down low. The engine is also a bit more efficient at full throttle, at full throttle altitudes with a power setting of around 65%.
Ideally the 182 should be leaned whenever below 75 %, including taxying.
No experience of a 6-300, but expect similar performance for another six-ten litres per hour. It is fuel injected so fuel consumption per hp may be a bit better.