Frequently Asked Questions
Low Sulfur Gasoline

The Environmental Protection Agency's national low sulfur gasoline program began on January 1, 2004. This program will reduce the amount of sulfur in gasoline in steps and will be phased in over 4 years. The EPA adopted this program several years ago to allow petroleum refiners the time they needed to modify their equipment to produce this less polluting gasoline.

Why is the sulfur contained in gasoline being reduced?
The principal reason for reducing the sulfur content of gasoline is to improve the efficiency and effectiveness of catalytic converters found on vehicles. The increased performance of the converters will result in lower tailpipe emissions of many critical pollutants, particularly nitrogen oxides and carbon monoxide. Less sulfur in the gasoline will also directly reduce emissions of sulfur dioxide and fine particulates.

By 2007 (when final sulfur levels are reached for most of the country) the following emission reductions are expected just from the lower sulfur levels in gasoline:
Reduction Compared To:
Pollutant Conventional
Gasoline		 Summer
Reformulated
Gasoline
Volatile organic compounds 11% 6%
Carbon monoxide 28% 20%
Nitrogen oxides 11% 6%
PM2.5 8% 3%
Sulfur dioxide 61% 35%

Where will low sulfur gasoline be used?
This is a nationwide program instituted by EPA. The new lower sulfur standards will be applied to all grades of gasoline. Gasoline stations, nationwide, will sell only low sulfur gasoline after January 1, 2004.
Will low sulfur gasoline affect my car or its performance?
The low sulfur gasoline will lead to longer life and better performance of the catalytic converter. There will not be any negative mechanical or performance impacts on your vehicle.
Will low sulfur gas affect gas mileage?
No. Lowering the sulfur content of gasoline does not change its energy density (BTUs per gallon). A slight (3%) but noticeable drop in gas mileage occurred when reformulated gasoline was introduced into southeastern Wisconsin, due the required use of an oxygenate, usually ethanol.
Will there be an increase in the price?
When making this rule, the EPA estimated that the additional refining needed to reduce the sulfur levels would add one to two cents to the price of a gallon of conventional gasoline. However, the summertime gasoline sold in southeastern Wisconsin already has reduced sulfur content, so the expected price increase in southeastern Wisconsin is expected to be less marked.
How does it relate to reformulated gasoline?
The reformulated gasoline (RFG) sold during the summer in southeast Wisconsin is a low-sulfur fuel. This rule will require the lower sulfur content found during the summer to be in force year round. The sulfur content of RFG will continue to decline along with the content found in conventional gasoline as the standards become tighter in 2005 and 2006.
Are any supply problems expected?
Some refineries have been making low sulfur gasoline in limited quantities for some time. Many major refineries in the upper Midwest have been upgrading their facilities this fall to comply with the lower sulfur requirements. Neither the Department of Energy, the EPA nor the DNR anticipate any supply disruptions this fall. In some areas, low sulfur gasoline is already available to consumers ahead of the January 1, 2004 deadline.
What if I have more questions?
Contact Larry Bruss, Section Chief, Regional Pollutants and Mobile Sources Section, at 608/267-7543.

Mobile Sources || Air Management

Last Reviewed: January 2004
Next Review: January 2007
Last Revised: Tuesday January 16 2007