Foreign-dependent pricing policy in-petroleum sector has led the market opportunists and transportation sector drivers to seek alternative cheaper fuels for diesel engines in Turkey. A new generic fuel blend of virgin/nonstandard base oils and/or low taxation wastes (waste lubricants, mineral oils, heavy solvent formulations etc.) with diesel fuel called number 10 lube (NTL) has been widely used for such purposes in public transportation vehicles or trucks over the last decade. Therefore, this study was conducted to characterize the fuel properties of NTLs to evaluate the probable impacts on engine performance and exhaust emissions. All tests (density, viscosity, flash point, pour point, water content, sulfur content, volatile content, acid number, base number, corrosiveness, color and Fourier Transform Infrared Spectroscopy analysis) were conducted at an accredited fuel analysis laboratory. The results showed a large fluctuation in NTL properties among the dealers or location. The outlier values observed for various physicochemical parameters indicated adulteration with different types of waste oils (vegetable, cooking, engine, mineral) and solvents in NTLs which make them unsuitable for diesel engines. Such an adulteration case is exceptional but fuel misuse is a common problem in the world, hence, should be managed properly and tackled with implementation of appropriate taxes. (C) 2015 Elsevier B.V. All rights reserved.