A salvage team remained on board the container ship Rena on Thursday night, transferring oil and lubricants from the engine room to a central tank.
Maritime New Zealand says the team of three kept power and pumping systems operating overnight.
Conditions are good to continue pumping and the rest of the salvage team will be back on the ship on Friday morning.
An estimated 358 tonnes of oil still remain in a submerged starboard tank.
