TBN Retention of Engine Oil - Improvements through Diesel Fuel Stabilization

Transcription

1 MARYNINTERNATIONAL RESEARCH LABS 201-1MIP-1012 TBN Retention of Engine Oil - Improvements through Diesel Fuel Stabilization Revised: October 2011

2 ABSTRACT Mass Transit Bus Fleets in Curitiba Brazil examines the effect of fuel stabilization and fuel system cleanliness using a fuel system antifoulant (PowerUp BlackOUT). over a period of 2 months. 145 buses participated in a blind study to determine the effectiveness of the product on combustion efficiency as measured by changes in TBN Retention, Oil oxidation, Nitration, and soot levels. Used Oil Analysis was used to measure the change in oil parameters that indicate more efficient combustion resulting from the use of the anti-foulant. For 4 months (March 2011 to June 2011) base line data was collected on the 145 buses. The anti-foulant was then added to the fuel and data collected for the following 2 months (July 2011-Aug 2011). Changes in the TBN Retention, oil oxidation, nitration and soot levels all showed improvements over the testing period as a strong indicator of improved combustion efficiency as a result of the use of PowerUp BlackOUT. This test was performed as a blind test meaning that the operators were not informed of any adjustments to the fuel to eliminate uncertainty. Testing sample size was large enough (145 buses) to be confident in the overall results based on model year and engine type. The data collection and analysis was performed in cooperation with the Mass Transit Authority and Innospec Fuel Specialties (a Tier 1 fuel additive supplier and partner with MARYN International in the development of the PowerUp fuel products.) TBN Retention / Fuel Stabilization Page 2 of 7

3 INTRODUCTION: Curitiba Brazil has a metro population of 3.6 million people and boasts of the lowest rates of ambient air pollution in the entire country. This is facilitated by a heavily used, low cost BRT (bus rapid transit) system that services the entire city. The transit system is used by 85% of the population (over 3 million people) for travel throughout the city. The transit system fleet contains over 1100 buses of various model years and engine types, primarily the Mercedes Benz OM924LA engines. Of 145 buses that were selected for the testing procedure, 2 model year groups and 3 engine types were selected. All 145 buses use the same fuel (B5 S50, Brazilian Source) and the same oil (Shell Rimula R3 X - 15W 40, API CI-4) and maintenance schedule. MARYN International produces lubricant products for many industries. Established in 1977 under the original name PowerUp Lubricants, MARYN has grown from a small sales operation to a large-scale lubricant manufacturer with international reach. Recognized for innovations in environmentally friendly and high performance lubrication, MARYN continues to be a source of innovation and improvement for fuel products used in mass transit and on/off highway operations. MARYN routinely partners with qualified Tier 1 suppliers to obtain the best possible ingredients in their products. Innospec Fuel Specialties produce Refinery fuel specialties and performance ingredients for major fuel suppliers throughout the world. PowerUp fuel products are formulated with to provide improved performance where base fuel quality does not meet the OEM fuel specifications or operating conditions require improved performance. This field test was performed following a strict maintenance program by the Curitiba Brazil Mass Transit technicians with the support of Innospec Fuel Specialties and the MARYN research lab. Regular oil analysis was completed and trends were used to determine the results found within this report. PowerUp BlackOUT is a diesel fuel system anti-foulant that contains a powerful detergent and fuel stabilization package designed to clean out deposits within the fuel system and prevent the formation of new deposits by greatly improving the thermal stability of the fuel and eliminating coking. This detergent and stabilization package is based on proprietary technology developed for MARYN by Innospec Fuel Specialties. Fuel degradation (coking) occurs as a result of high pressures and heat found in pressurized common rail (HPCR) fuel delivery systems. Biodiesel blends are especially vulnerable to thermal degradation. In many cases thermally stressed fuel is returned to the tank via the fuel return line and can be seen through a blackening of the fuel in the tank or sooty material collecting in fuel filters. Regular use of PowerUp BlackOUT and PowerUp DieselFX (which contain the same detergent and stabilization package) can help to correct issues related to thermal fuel degradation or prevent future problems. This fuel stabilization process results in improved combustion efficiency which was measured in this trial through oil analysis key indicators. 145 buses were selected for the testing procedure. Of these 61 buses were model years spanning buses were model years spanning The engine types included Mercedes Benz models OM924LA (~70%), OM906LA (~ 20%) and OM904LA (~10%). The objective of this study was to determine how effective the antifoulant performed in improving combustion. This improvement was measured through key indicators of oil analysis that are affected by combustion efficiency. Used Engine Oil analysis can be used to examine trends that can indicate varying levels of engine and engine oil performance. In the case of combustion efficiency there are several key indicators that routinely appear in oil analysis which can be monitored to discover improvements or deficiencies in the combustion process. TBN Retention / Fuel Stabilization Page 3 of 7

4 KEY INDICATORS: Soot Levels (Lower is Better): Efficient combustion produces lower soot content. High levels of soot contribute negatively to lubricating oil degradation, impact engine wear, forms sludge in engine. Oxidation (Lower is Better): Efficient combustion produces less by-products of combustion (acids, etc), thus slowing down oxidative degradation of lubricating oil. Nitration (Lower is Better): Lower nitration (NOx) is related to better combustion efficiency. Nitrates enter lube oil by blow-back combustion gases past compression rings. Moisture in lube oil will react with nitrates to form nitric acid, which again contributes to oxidative degradation of lube oil. TBN Retention (Higher is Better): Significant quality indicator for life of lubricating oil. Higher number = higher buffering capacity of lube oil vs. combustion acids. Dependent on type / manufacturer of oil (eg Shell TBN = 9, Petronas = 16). Higher TBN at end of a trial indicates better TBN Retention which directly correlates to less formation of by-products of combustion acids, a suitable temperature of engine operation, etc... and thus extended life (use) of lubricating oil. Note: combustion efficiency is not the only contributing factor to these key indicators however if all other contributing factors (filtration, maintenance intervals, operating conditions etc) remain constant it is possible to determine the effect of improved combustion efficiency through fuel stabilization on these oil analysis indicators. DISCUSSION Following the existing maintenance program for the engines, oil samples were collected during routine maintenance from March 2011 until June 2011 to obtain a baseline in the key indicators found the oil analysis. The PowerUp BlackOUT fuel system anti-foulant was then added to the fuel from July 2011 until August 2011 with oil samples collected on the same schedule. PowerUp BlackOUT fuel treatment ratios are 1:1500 (20L of BlackOUT to L of Diesel Fuel). The data was compiled and grouped by model year and engine type and aggregate data compared to the baseline results. Soot levels, Oxidation and Nitration all decreased during the testing period while TBN Retention increased indicating that the anti-foulant was improving combustion efficiency. The resultant improvement in used oil quality could actually allow for extended service life of the fluid. Additional benefits from improved combustion can also include improved fuel economy, reduced tailpipe emissions, extended fuel system component life (injectors, pumps, filters etc). In order to minimize the possibility of error during the testing period no changes were made to the preventative maintenance (PM) schedule or fueling procedures for the operators. Drivers were not even told that a test was being conducted to minimize the impact of operator influenced conditions (such as idle time, driving habits etc). Sample sizes were large enough to have confidence in the overall trend indicated in the compiled oil analysis data. It was anticipated that the fuel stabilization and fuel system clean-up resulting from the use of BlackOUT would be clearly indicated in the used oil analysis results. TBN Retention rates alone indicated possible oil life extension of 30% following the Mass Transit oil life procedures. TBN Retention / Fuel Stabilization Page 4 of 7

5 DATA COLLECTION AND ANALYSIS The buses selected use Shell Rimula R3 X engine oil, SAE Viscosity 15W 40, with API service category CI-4. The following chart contains the published specifications of this oil: Properties Method Shell Rimula R3 X - 15W 40, API CI-4 Viscosity Grade 15 W 40 Kinematic 40ºC (mm²/s) ASTM D Kinematic 100ºC (mm²/s) ASTM D Dynamic -15ºC (mpa s) ASTM D Dynamic -20ºC (mpa s) ASTM D Viscosity Index ASTM D ºC (kg/l) ASTM D Flashpoint (COC) ºC ASTM D Pourpoint ºC ASTM D97-39 Total Base Number (TBN) Mg KOH /g ASTM Sulphated Ash (%) ASTM D Oil samples were analyzed by a third party lab over the course of the 6 month trial. Results were then compiled for the entire baseline period and testing period by model year group and engine type with a average for each model year group provided. The baseline results were then compared to the testing results and expressed as a % improvement for each of the key indicators. TBN Retention (Higher is Better): Significant quality indicator for life of lubricating oil. Higher number = higher buffering capacity of lube oil vs. combustion acids. Dependent on type / manufacturer of oil (eg Shell TBN = 9, Petronas = 16). Higher TBN at end of a trial indicates better TBN Retention which directly correlates to less formation of by-products of combustion acids, a suitable temperature of engine operation, etc... and thus extended life (use) of lubricating oil. TBN Retention / Fuel Stabilization Page 5 of 7

6 Oxidation (Lower is Better): Efficient combustion produces less by-products of combustion (acids, etc), thus slowing down oxidative degradation of lubricating oil. Nitration (Lower is Better): Lower nitration (NOx) is related to better combustion efficiency. Nitrates enter lube oil by blow-back combustion gases past compression rings. Moisture in lube oil will react with nitrates to form nitric acid, which again contributes to oxidative degradation of lube oil. TBN Retention / Fuel Stabilization Page 6 of 7

7 ANALYSIS The use of oil analysis key indicators to show evidence of combustion efficiency clearly indicates that there will be variations in the data results based on many factors - including engine type and equipment model year. As shown through the sampling of 145 buses from the Mass Transit fleet the overall improvement rate of each of the key indicators can be grouped an analyzed providing a universal average level of improvement. TBN Retention: The Shell Rimula R3 X - 15W 40, API CI-4 engine oil starts with a TBN of 10.8 which through the process of time can be reduced as to as low as 3.0 during the course of a PM service interval. In the case of the buses sampled, the same service interval showed that the total base number was retained (meaning the TBN was 14.9% higher at the end of the service interval) better with the use of PowerUp BlackOUT than the baseline (prior to the introduction of BlackOUT). Oil Oxidation: By-products of combustion contribute to oil oxidation process (this typically results in a thickening of the oil). These by-products can also contribute to the development of varnish and sludge buildup in the engine crankcase. In the case of the buses sampled, the samples showed lower levels of oil oxidation ( % lower than the baseline samples over the same service intervals) a clear indicator of improved combustion efficiency. Nitration: Nitrates enter the oil through blow-by (gases which enter the crankcase past the compression rings). These nitrates when combined with moisture in the oil form acids which can contribute to TBN reduction and oil oxidation. In the case of the buses sampled, nitrate levels were dramatically decreased when compared to the baseline samples over the same service intervals. Through the use of the highly concentrated detergent and stabilization package found in PowerUp BlackOUT, the average TBN retention improved by %, the oxidation levels decreased by % and the nitration levels decreased by %. These levels clearly indicate improved combustion efficiency by introducing the fuel system anti-foulant. CONCLUSIONS The purpose of this study was to examine the ability of PowerUp BlackOUT to improve combustion efficiency through fuel system cleanliness and fuel stabilization. The method of measurement was key indicators in the used oil analysis results. Improvements to TBN Retention, Oil Oxidation and Nitration were clearly observed over the testing period. Through the use of the unique properties of PowerUp BlackOUT as a fuel system anti-foulant and to prevent thermal fuel degradation it is possible to improve combustion efficiency to the point of improving the service life and key characteristics of engine oil. The additional benefits of efficient combustion also include improved fuel efficiency and a reduction in harmful tailpipe emissions. When accompanied with a cetane improver (such as the technology found in PowerUp DieselFX) further efficiencies may also be achieved. This study was conducted with 145 buses selected out of the entire fleet of 1100 units. The overall TBN retention improvement of 14.9% could greatly impact the fluid service life of engine oil and allow for extended service life and reduced oil consumption. The combustion efficiencies observed will also prove to increase fuel economy (~5% consumption reduction was observed during the test period) and reduce harmful emissions which can greatly contribute to a reduction in the Mass Transit system carbon footprint. Note: MARYN Research would like to acknowledge the contribution Innospec Fuel Specialties in the development and collection of the data contained within this report. TBN Retention / Fuel Stabilization Page 7 of 7