Oregon Revised Statutes Revenue and Taxation § 319.860

(1) Every person producing, manufacturing, importing, distributing, storing, transporting or otherwise handling fuel shall maintain and keep in this state for a period of not less than three years such records, receipts, invoices and other pertinent papers in such form as the Department of Transportation may require.

(2) The department may examine during normal business hours the books, papers, records and equipment of any person producing, manufacturing, importing, distributing, storing, transporting or otherwise handling fuel and may investigate the character of the disposition which any such person makes of fuel in order to determine whether all taxes due under ORS 319.510 to 319.880 are being properly reported and paid.