Single cylinder and multicylinder direct injection engines from the same engine family were used to evaluate the performance of stabilized diesel fuels containing methanol, ethanol, water, and chemical stabilizer. Engine speed and load conditions were selected to provide sufficient smoke and particulate emissions for accurate measurement. All fuels were operated at equal energy input rates for the engine being tested. The stabilized fuels containing alcohols had relatively minor effects on the HC, CO, and NOx emissions and engine brake efficiency for either the single or multicylinder engine. The water microemulsion fuel demonstrated a tendancy for increased HC and CO emissions, and minor changes in the NOx and brake efficiency for both engines. Both engines demonstrated reduced smoke and particulate emissions for the stabilized alcohol and water microemulsion fuels. These reductions ranged from only a few percent to over 50% and were accompanied by significant increases in the Soluble Organic Fraction of the particulate. © Copyright 1983 Society of Automotive Engineers, Inc.