Tosco’s loss widened but its outlook brightened.

Tosco, an oil and gas company based in Santa Monica, restated its first-quarter loss to $100.8 million to reflect a $45-million writedown of the value of its oil and gas assets. Earlier, Tosco had reported a loss of $55.8 million for the quarter. The company said it expects a return to profitability in the current period. Tosco is the latest energy company to restate first-quarter results after the Securities and Exchange Commission refused to waive a rule that the value of oil and gas holdings be assessed each quarter.