Engine: October 2003 Z18XE Auto (97,800km)

Current oil: Nulon Full Synthetic 10w40

Previous oil: Whatever crap Holden used in their $99 service. Presumably some cheap mineral 15w40. After 9,000kms, literally black. Filter was packed with crap.

Feeling: Can't feel or hear the engine running from inside the car when stopped at the lights. Before oil change it made a few concerning noises that I thought were timing belt related and sounded like a sick tractor. Engine now revs more freely, idles silently and without any vibration. Fuel economy has improved 0.2l/hr when idling.