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The majority of low sulphur automotive diesel fuels marketed today are treated with an additive to enhance the lubricity of the base fuel. Field experience has shown that in order to achieve the full benefits of the low sulphur diesel fuel, the lubricity additive must not only provide sufficient lubricity performance to protect sensitive diesel fuel pumps, but must have no undesirable side effects. These potential side effects include: 1) Degrading the properties of the base fuel, 2) Interacting with crankcase lubricating oils, 3) Reducing the performance benefits of other fuel additives The oil and additive industries have developed a wide range of tests to evaluate the no-harm performance of lubricity additive packages and components. This paper describes many of these tests, with respect to their use in the development of a novel, lubricity additive package for City Diesel Fuel.

The ASTM D6121 (L-37) is a key hypoid gear lubricant durability test for ASTM D7450-08 (API Category GL-5) and the higher performance level SAE J2360. It is defined as the ‘Standard Test Method for Evaluation of Load-Carrying Capacity of Lubricants Under Conditions of Low Speed and High Torque Used for Final Hypoid Drive Axles’. Pass/fail is determined upon completion of the test by rating the pinion and ring gears for several types of surface distress, including wear, rippling, ridging, pitting, spalling and scoring. Passing the L-37 in addition to the other tests required for API Category GL-5 credentials, as well as the more strenuous SAE J2360 certification, requires in-depth formulating knowledge to appropriately balance the additive chemistry. This paper describes the results of ASTM D6121 experiments run for the purposes of better understanding gear oil durability.

The size and morphology of soot particles and agglomerates extracted from lubricating oil drawn from the sump of a diesel engine have been investigated and compared using Transmission Electron Microscopy (TEM) and Nanoparticle Tracking Analysis (NTA). Samples were prepared for electron microscopy imaging by both centrifugation and solvent extraction to investigate the impact of these procedures on the morphological characteristics, such as skeleton length and width and circularity, of the obtained soot. It was shown that centrifugation increases the extent of agglomeration within the sample, with 15% of the agglomerates above 200 nm compared to only 11% in the solvent extracted soot. It was also observed that the width of centrifugation extracted soot was typically 10 nm to 20 nm larger than that of solvent extracted soot, suggesting that centrifugation forces the individual agglomerate chains together.

Traditional methods for monitoring corrosion processes and mechanisms in real time can be both time consuming and challenging to interpret, especially when evaluations at multiple temperatures are required. Reported at SAE world congress 2017 by this author, a new method for measuring the change in resistance of a thin copper wire was applied to provide a way to monitor the corrosion of copper in situ. In this work, a copper alloy in thin wire form has been used to compare the corrosion rates to pure copper. New insights on the kinetics and mechanisms of corrosion in the presence of lubricant additives over a range of operating temperatures using the wire resistance test will be discussed. The corrosion processes observed here are highly dependent upon temperature. Making assessments of corrosion performance through elevated temperature differentiation testing can provide less optimal corrosion protection at the actual operating temperature condition.

Improvements in vehicle fuel efficiency continue to be a significant driver for all parties involved in the operation of automotive vehicles. The cost of vehicle ownership, energy security and the need to limit greenhouse gas emissions are all factors in driving the need to improve operating efficiency. One particular area of interest is engine lubricants which are known to have a significant effect on the overall efficiency of a vehicle. The decision to move to a more fuel efficient lubricant is enhanced since the incremental cost of introducing a fuel efficient lubricant is low in comparison to the potential fuel saving leading to a favourable economic decision for a fleet owner. This paper describes a study undertaken where upon two significantly different UK buses were taken directly from the FirstGroup fleet and used for a period of two weeks for fuel economy testing. The testing centres on two commercially available engine lubricants and was completed on a test track in the UK.

Modern automotive transmissions contain copper and copper alloys in the form of washers, bushings, brazes and electrical components. Corrosion that occurs with any of these components especially with electrical contacts can result in a malfunction of the vehicle control systems and loss of vehicle drivability. The compatibility of transmission lubricants with copper and copper alloys is an increasingly important consideration in the design of new additive technology. Traditional methods for monitoring corrosion processes and mechanisms in real time can be both time consuming and challenging to interpret, especially when evaluations at multiple temperatures are required. This work challenges some of the industry-held beliefs around lubricant additive corrosion processes, especially at elevated temperature (>130 °C).