A new soy-derived additive for unleaded gasoline has been developed by Schaeffer Manufacturing Co., the St. Louis firm that makes and sells SoyShield diesel fuel additive.

"This product increases lubricity by 40% compared with standard unleaded gasolines," says Jay Shields, Schaeffer's executive vice president. "That's the major benefit. New clean-air regulations limit the amount of lubricating elements - such as sulfur - in both gasoline and diesel."

The gasoline additive (as yet unnamed) also improves fuel economy by about 4% and contains upper-cylinder cleaners that help remove combustion deposits.

"When low-octane (typically 87 octane) gasoline is burned in a new engine, deposits often build up in the combustion chamber," notes Shields. "In 10,000 to 15,000 miles, these deposits can interfere with engine performance.

"That's why some drivers often switch to a higher-octane (and higher-priced) gasoline to restore engine performance. This additive cleans up those deposits and restores engine cylinders to near-new condition."

The price of the soy-based additive adds about 2 to the cost of a gallon of gasoline. But a 4% improvement in fuel efficiency more than offsets the additive cost, Shields says. He expects to bring the additive on the market early this year.

For more information, contact Schaeffer Manufacturing at 800-325-9962, or check the company's Web site (www.schaefferoil.com).