The final gasoline sulfur rulemaking amended 40 CFR § 80.46(a) to require the use of ASTM D 3246-96 to determine the sulfur content of butane. We did not intend to require the use of this new test method to be effective immediately.

We intended that it should take effect January 1, 2004, when a butane sulfur content standard becomes effective for refiners who produce gasoline by blending butane to previously certified gasoline. Until January 1, 2004, any appropriate ASTM method may be used for testing the sulfur content of butane. We intend to take regulatory action to clarify the effective date of the regulatory butane test method.