Getting more out of the Marsden Point refinery is one option being considered by Refining NZ to counter a persistently strong currency, intense competition and volatile refiner margins.
Shares in the company fell 5.5% after it made a profit of $32.6 million in 2012, a decrease of 5% compared with the same period a year ago.
Gross earnings fell 14% to $114 million, which Refining NZ chief executive Sjoerd Post said is due to the high New Zealand dollar and squeezed margins, which he's not expecting will ease over the coming year.
He said the company is trying to find ways to improve the performance of the equipment.
Mr Post said the refinery's through put was 2% better than it had ever achieved, while petrol, diesel and jet fuel were 4% up on the best ever year.
He said the company attempts to compensate for the margin by processing the best that it can.
NZ Refining, which supplies around 80% of New Zealand's refined fuels, is about 73% owned by BP, Mobil Oil, Caltex, and Greenstone Energy, which bought Shell Oil's domestic retail operations.
Its shares fell 15 cents to $2.55 on Wednesday.
