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The lubricity of low sulfur diesel fuel was evaluated using a Scuffing BOCLE device. Physical and chemical properties of diesel fuels were then used to correlate with fuel lubricity. It is concluded that lubricity is primarily determined by viscosity and di-aromatic content. A lubricity predictor (Lp) using a linear combination of the two parameters is proposed to predict fuel lubricity. These two parameters are interchangeable within normal ranges of viscosity and di-aromatic content of No.1 and No.2 diesel fuels. Fuel lubricity has been interpreted to be the result of hydrodynamic lubrication, which is largely a function of viscosity, and boundary lubrication, which is contributed to by the di-aromatic content.

Corrosive wear of non-ferrous engine components by lubricants is a concern of all major heavy duty diesel engine manufacturers since warranty on key engine components has been extended to 500,000 miles. Several commercial lubricants have been linked to premature cam and rod bearing failures induced by corrosion in certain fleets. Although the overall failure rate is low, specific fleets have experienced significantly higher failure rates due to the lubricants used. These failures usually occur at high mileages but less than 500,000 miles. This kind of slow corrosion easily escapes detection of engine tests contained in current oil specifications, and it represents a serious issue in long term warranty cost to diesel engine manufacturers. A comprehensive fleet database has been established to identify the most corrosive lubricants. These lubricants have served as reference oils to develop a corrosion bench test.