30 CFR § 75.1901
Diesel fuel requirements.
(a) Diesel-powered equipment shall be used underground only with a
diesel fuel having a sulfur content no greater than 0.05 percent and a
flash point of 100 deg. F (38 deg. C) or greater. Upon request, the
mine operator shall provide to an authorized representative of the
Secretary evidence that the diesel fuel purchased for use in diesel-
powered equipment underground meets these requirements.
(b) Flammable liquids shall not be added to diesel fuel used in
diesel-powered equipment underground.
(c) Only diesel fuel additives
that have been registered by the Environmental Protection Agency may be used in diesel-powered equipment underground.