ORS § 319.370
The Department of Transportation, or its duly authorized agents, may make any examination of the accounts, records, stocks, facilities and equipment of dealers, brokers, service stations and other persons engaged in storing, selling or distributing motor vehicle fuel or other petroleum product or products within this state, and such other investigations as it considers necessary in carrying out the provisions of ORS 319.010 to 319.430. If the examinations or investigations disclose that any reports of dealers or other persons theretofore filed with the department pursuant to the requirements of ORS 319.010 to 319.430, have shown incorrectly the amount of gallonage of motor vehicle fuel distributed or the tax, penalty or interest accruing thereon, the department may make such changes in subsequent reports and payments of such dealers or other persons, or may make such refunds, as may be necessary to correct the errors disclosed by its examinations or investigations.
ORS 319.370