Section 7. Any person who shall buy any fuel other than aviation fuel on which an excise has been paid or is chargeable under this chapter, and shall consume the same in any manner except on a farm for farming purposes or in the operation of motor vehicles upon or over highways, whether or not such vehicles are registered under the provisions of section five of chapter ninety, and any person who transfers into another state fuel on which the excise has been paid or is chargeable under this chapter, and pays an additional excise or other tax which is properly due to such other state on such fuel so transferred, shall be reimbursed the amount of said excise in the manner and subject to the conditions hereinafter set forth; provided, however, that any turnpike constructed by the Massachusetts Department of Transportation in accordance with chapter three hundred and fifty-four of the acts of nineteen hundred and fifty-two, as amended, shall not be considered a highway for the purposes of this chapter until such turnpike shall have become a part of the state highway system as provided in section seventeen of said chapter three hundred and fifty-four. All claims for reimbursement shall be for not less than one dollar, shall be made by affidavit in such form and containing such information as the commissioner of revenue shall prescribe, shall be accompanied by original invoices or sales receipts of fuel and in the case of claims for reimbursement for tax on fuel consumed on said turnpike, shall be made with respect to a calendar half year and shall be accompanied by the toll receipts given to users of said turnpike or invoices rendered to such users by said Authority. All claims for reimbursement shall be filed with the commissioner within two years from the date of purchase or invoice of fuel; except claims for reimbursement of the excise paid for fuel used in producing or generating power for the operation of watercraft of every description, other than a seaplane, which shall be filed within six months from the date of purchase or invoice of such fuel. Such toll receipts given to users of said turnpike or invoices rendered to such users by the said Authority shall be accepted by the commissioner as evidence of the use on said turnpike of fuel in the proportion of one gallon for each fifteen miles of indicated travel by passenger cars, ambulances, hearses, motorcycles and light trucks, and in the proportion of one gallon for each five miles of indicated travel by all other trucks and buses. No claims for reimbursement for tax on fuel consumed on said turnpike shall be allowed unless it shall appear from said toll receipts or invoices and from said invoices or sales receipts of fuel that the purchase of the fuel which is the basis for the claim of reimbursement took place on the same or any one of the three preceding calendar days as the travel on said turnpike or unless evidence satisfactory to the commissioner is furnished that such fuel was transferred from bulk to the vehicle tank within the same period. The commissioner may require such further information as he shall deem necessary for the determination of such claims, and shall transmit all claims approved by him to the comptroller for certification; and the amount approved by the commissioner and certified as aforesaid shall be paid forthwith from the proceeds of the excise tax levied under this chapter, without specific appropriation.