Auto Alliance spokesman Dan Gage says that running lower-quality fuels reduces engine performance and can lead to damage.  Refiners dispute that.  And 85 octane gas has commonly been used as a fuel for higher altitudes in western South Dakota. The state Department of Public Safety is writing rules to clarify the legal status of 85 octane fuel and specify how it must be labeled.  Government officials say mislabeled fuel has been found in several cities in eastern South Dakota.Suppliers say a constant threat of fuel shortages is the reason.

AP