91.308 Lubricating oil and test fuel.§ 91.308 Lubricating oil and test fuel.
(a) Lubricating oil. (1) Use the engine lubricating oil which meets the marine engine manufacturer's requirements for a particular engine and intended usage. Record the specifications of the lubricating oil used for the test.
(2) For two-stroke engines, the fuel/oil mixture ratio must be that which is recommended by the manufacturer. If the flow rate of the oil in the engine is greater than two percent of the fuel flow rate, then the oil supplied to the engine must be added to the fuel flow in the emission calculations described in § 91.419 and § 91.426. Good engineering judgment may be used to estimate oil flow when oil injection is used.
(b) Test fuels - certification. The manufacturer must use gasoline having the specifications or substantially equivalent specifications approved by the Administrator, as specified in Table 3 in appendix A of this subpart for exhaust emission testing of gasoline fueled engines. The specification range of the fuel to be used under this paragraph must be reported in accordance with § 91.109(d).
(c) Test fuels - service accumulation. (1) Unleaded gasoline representative of commercial gasoline which will be generally available through retail outlets must be used in service accumulation for gasoline-fueled marine engines. As an alternative, the certification test fuels specified under paragraph (b) of this section for engine service accumulation. Leaded fuel may not be used during service accumulation.
(2) The octane rating of the gasoline used may not be higher than 4.0 research octane numbers above the minimum recommended by the manufacturer and have a minimum sensitivity of 7.5 octane numbers, where sensitivity is defined as research octane number minus motor octane number.
(d) Other fuels may be used for testing provided:
(1) They are commercially viable,
(2) Information, acceptable to the Administrator, is provided to show that only the designated fuel would be used in customer service,
(3) Use of a fuel listed under paragraph (b) of this section would have a detrimental effect on emissions or durability; and
(4) The Administrator provides written approval of the fuel specifications prior to the start of testing.