What’s the cost of restarting an oil refinery just two months after it was shut down? About $27 million, according to the new owner of Tesoro Corp.’s Kapolei oil refinery.

Par Petroleum Corp., which announced this week that it is buying the refinery, will reverse the mothballing process Tesoro just went through after it closed the refinery April 29.

Restarting the refinery will take a crew of 400 to 500 workers until early September to complete, a Tesoro official estimated.

And who gets to pay for that?

Houston-based Par Petroleum agreed to pay the first $15 million for “startup expenses,” the company said in a filing with the Securities and Exchange Commission. Tesoro will pay the next $5 million, with Par Petroleum picking up any expenses in excess of $20 million, according to the filing.

Tesoro, which had been searching for buyer for the refinery since January 2012, shut it down at the end of April when no deal had been struck. It then began the process of preserving the refining equipment so that it could be restarted in the event a buyer was eventually found. Tesoro would not say how much it cost to mothball the operation.

After the shutdown, Tesoro continued to supply customers with refined products such as gasoline and jet fuel by shipping them in to its offshore mooring near Barbers Point.

On Monday Tesoro announced that it had a deal to sell the operation and its chain of 31 gas stations to Par Petroleum for $75 million cash, plus a bonus of up to $40 million over three years if certain sales targets are met. On top of that Par Petroleum will pay an estimated $225 million to $275 million for Tesoro’s inventory of refined petroleum products.

The sale prevented the loss of up to 165 jobs that would have been eliminated had the refinery been closed permanently.

Par Petroleum, an energy company based in Houston, also disclosed that it replaced its chief executive officer on the day it announced the Tesoro acquisition.

William Monteleone, who has been a director for Par Petroleum since August, was named to replace John T. Young, who had served as CEO since September.

Par Petroleum will finance the acquisition through issuing $200 million of common stock and more than $125 million in loans.

One of the private equity firms that has agreed to buy the new shares is controlled by Chicago-based real estate tycoon Sam Zell. Zell also is chairman of the board of New Jersey-based Covanta Energy Corp., which operates the city-owned HPOWER waste-to-energy plant in Campbell Industrial Park