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Cloud point depressants (CPD) have been successfully used for many years in low-sulfur diesel fuels. For over ten years, custom-designed, specialty polymer chemistry has enabled refiners to meet cloud point (CP) guidelines with substantially less kerosene. This translates into greater refined yields through cut-point adjustment upgrades and the potential for diverting kerosene to more lucrative market opportunities, such as jet fuel. The practice of cut-point downgrades to gas oil can be costly because diesel fuel generally has greater value. Kerosene dilutions have historically been as high as 30%-40% by volume with low-sulfur diesel fuels [1, 2]. While kerosene addition enables fuels to reach CP guidelines, it may negatively impact the fuel's energy content, cetane number, lubricity, flash point and density. Properly designed CP additives are able to substantially reduce or even eliminate the need for kerosene, thus substantially reducing refinery costs.

A new generation of fluid technology using novel diesel fuel detergent/dispersant chemistry provides a multitude of beneficial effects to the diesel engine, especially the latest model designs. In addition to improved injector, valve and combustion chamber deposit removal, the additive restores power, fuel economy, performance and emission levels1. Positive observations have also been documented along with improved performance concerning crankcase lube viscosity, soot loading and TBN retention. An even greater added benefit is the inherent capability of the fuel additive to deal with several EGR issues now prominent with the introduction of new engines. Recent research, reported herein, has uncovered the extensive efficacy of this chemistry for piston durability and neutralization of ring corrosion phenomena. All of the beneficial additive attributes are further enhanced with increased oxidative and thermal fuel stability and no loss of filterability.

A fleet test study was initiated to compare the use of a unique boundary chemistry (UBC) containing PTFE engine treatment, as a supplement to a current 10W-30, API SJ/GF-2 motor oil, versus the use of the oil without any supplement. The test was conducted with a taxi fleet of 1998 Chrysler 2.4L minivans. The factory-fill oil was drained after 5 thousand km and the group of vehicles entered the test program designed as a double-blind study, wherein, neither the drivers nor analysts knew the identities of reference and treated engines. Half of the taxis received a one-time application of the engine treatment. Subsequent oil drain intervals were conducted every 6.5 thousand km so that at 11 thousand km a baseline and treated engine were pulled from the vans and sent to the laboratory for analysis. The rest of the fleet continued on to 50 thousand km, six oil changes later, when two more engines were obtained as before. The last data point was at the 82 thousand km mark.

Analytical information supplemental to data previously described in Parts 1 & 2 (SAE 900814) is presented. Solid-sample injection gas chromatography and X-ray fluorescence were employed to characterize the particulates collected on Pallflex and Fluoropore filters. The complete preweighed filter was thermally desorbed and separated by capillary GC with simultaneous flame ionization (FID), thermal conductivity (TCD), nitrogen/phosphorus (NPD), and flame photometric (FPD) detection. Results are reviewed in terms of: % non-volatiles, % volatiles (fuel and lube oil contributions correlated to various engine speeds and loads), as well as detectable nitrogen, phosphorus, or sulfur compounds.