What Is “Petroleum Diesel?”
We defined petroleum diesel as “on-highway” low-sulfur diesel made from crude oil. Recent regulations
promulgated by the U.S. Environmental Protection Agency (EPA) as part of its enforcement of the 1990
Clean Air Act Amendments set tougher restrictions on diesel used on the road versus diesel used off the
road. The “on highway” diesel must now meet new limits for sulfur content that are an order of
magnitude lower than previously allowed (0.05 wt% versus 0.5% sulfur). We restrict our evaluation of
petroleum diesel to this new low-sulfur diesel.