The buyer of Tesoro Corp.’s Kapolei oil refinery estimates it will take about $27 million to carry out the maintenance necessary to restart the facility, which has been idle since late April.

Par Petroleum Corp., which announced this week that it is buying the refinery, 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 down the facility on April 29 and mothballed, or preserved, the refining equipment in the event a buyer was eventually found.

After the closure Tesoro began shipping in refined products to fulfill its contracts with customers. A Tesoro official on Wednesday estimated that it will take until early September to complete the maintenance and restart the refinery.

On Monday Tesoro announced that it had secured a deal to sell the refinery to Par Petroleum for $75 million in cash, plus up to $40 million more over three years based on the facility’s performance.