Endurance Test with TOHO 9000 Oil Additive on the Liebherr D926 TI-E Engine

(Bore x Stroke: 122 x 142 mm) Final Report

Contents

1. Introduction

2. Summary and Conclusions

2.1. Comparison of the Engine Performance and Emissions with- and without TOHO 9000
2.2. Lube Oil Analysis Results
2.3. Visual Inspection
2.4. Further Endurance Test Results
2.5. Conclusions

3. Test Results

3.1. Comparison Tests (Engine with and w/o TOHO)
3.2. Endurance Test Procedure
3.3. Chemical Lube Oil Analysis Results of the 1250 Hours Endurance Test with TOHO 9000
3.3.1. General
3.3.2. Viscosity, Insoluble's and Dispersant Efficiency
3.3.3. TBN
3.3.4. Wear Metals
3.4. Visual Inspection of the Main Engine Components after the 1250 Hours Test with TOHO 9000
3.5. Further Endurance Test Results

1. Introduction

Based on the agreement between TOHO International Pte Ltd. and AVL dated 04-June-I 996, AVL was performing an engine durability program with the lube oil additive TOHO 9000 in order to demonstrate its long term effects on lube oil aging behavior (viscosity, TBN, Insoluble's, wear metal content etc. indicative for oil change intervals) as well as on engine performance and emissions.

The test procedure was the MAN 500 hours test which includes constant load phases at rated power and peak torque and intermittent load phases (low idle to rated power).
This test procedure was run two and a half times accumulating a total endurance test running time of 1250 hours which is equivalent to a vehicle running distance of approximately 100.000 km.

An identical engine was run at LMB (LiebhelT Machines Bulle) for 500 hours with standard lube oil without any additional additive and the results will be compared to those of AVL’s test with
TOHO 9000.

The 1250 hours test at AVL was performed without an oil change whilst the regular interval for changing the engine lube oil is 250 hours according to the engine manufacturer’s standards. A mixture of 85% standard lube oil (Shell Rimula TX 10W30) and 15% TOHO 9000 was used (15% TOHO is more a blending component than an additive, however we name it “additive”). The oil consumed was regularly topped up with standard lube oil whilst the amount of oil taken out every 50 hours for the chemical analysis was replaced with the mixture.

2. Summary and Conclusions
The results obtained during the subject test program are split up and summarized as follows:

2.1. Comparison of the Engine Performance and Emissions with- and without TOHO 9000

The comparison test was run at AVL before the endurance test program with the identical engine under exactly the same engine operating and similar ambient boundary conditions. Therefore, a conclusive judgment can be made:

Full load performance

The maximum power output, the fuel consumption and smoke emission is equivalent within the measurement accuracy.

The blowby of the engine dropped by approximately 5-8% under high speed/full load conditions, indicating some positive effect of TOHO 9000 with respect to the scaling capabilities of the piston-piston ring - cylinder liner area.

ECE R49 emission test

Overall the same good level of engine-out emissions was observed for all measured emission components (NOx, HC, CO, particulates).

2.2. Lube Oil Analysis Results

The oil analysis (TBN, viscosity, Insoluble's and wear metals) does not indicate any problems after 1250 hours running time.

TBN (ASTM-D-664 procedure) of the lube oil with 15% TOHO 9000 shows an unusually low degradation even after 1250 hours running time.

Adding TOHO 9000 to a SAE 10W30 lube oil results in a viscosity increase to a SAE 10W50 lube oil class and a drop with a short running time of 50 hours to a SAE 10W40 class oil. The viscosity was then stable within the SAE I 0W40 class up to 1250 hours running time.

The Dispersant activity of the lube oil containing TOHO 9000 is still excellent after 1250 hrs. engine running time.

Wear metals show a normal more or less linear increase in mg metal and this means TOHO 9000 does not influence engine wear.

2.3. Visual Inspection

From the visual inspection of the main engine components such as engine block, cylinder liner, pistons, piston rings, valves, manifolds etc. of the engine run for 1250 hours along the MAN endurance test cycle, it can be concluded that:

.

Taking into account that a standard lube oil - Shell Rimula TX 1 0W30 containing 15% of TOHO 9000 - had been used without an oil change and without changing the oil filter over 1250 hours along a quite severe test procedure, the visual condition of the engine was judged to be very good.

2.4. Further Endurance Test Results

The engine full load performance and emissions as well as the lube oil consumption was recorded along the endurance test period in regular intervals of 250 hours.

A total amount of 63.5 liters lube oil (TX 1 0W30 w/o TOHO) had to be refilled over the running time of 1250 hours to compensate the natural lube oil consumption. This is approximately 3 times the oil filling volume of the subject engine.

None of the results indicated any abnormal engine behavior.

As no comparison data of engines of the same type run over the same running time and test cycle without TOHO are available (statistical scatter band), the obtained engine results cannot be correlated to the use of TOHO 9000 and figure as additional information only.

2.5. Conclusions
Based on the lube oil analysis as well as on the visual inspection results of the engine main components, an extension of the running time to more than 1250 hours can be recommended.

No negative influence of the use of TOHO 9000 with respect to engine wear, power output or engine emissions arc indicated.

3. Test Results

3.1. Comparison Tests (Engine with and w/o TOHO)

Before the start of the endurance test program, it was agreed to compare the engine full load and ECE R49 emission results of the Liebheii D926 TI-E engine using a standard lube oil first and then a mixture of 85% standard lube oil plus 15% TOHO 9000.

As standard oil Rimula TX 15W40 and 10W30 oils were used (see fig. D3). Because the results just differ within the measurement accuracy, only the latter has been used for comparison. Subsequently, the oil was drained and replaced by a mixture of 85% Rimula TX 1 0W30 and 15% TOHO 9000. The engine was warmed up for approx. 15 minutes under idling conditions to assure a good mixing and after 6 hours running at various loads, the comparison full load test was performed.

As these tests have been carried out with the identical engine and the engine operating conditions (such as engine speed, boost pressure and temperature, fuel and oil temperature as well as coolant temperature etc.) were kept constant and also the ambient conditions (ambient temperature, barometric pressure) were similar, the obtained results allow conclusive judgments:
As illustrated in fig. Al, the full load performance (maximum power output, fuel consumption, smoke emission) is equivalent within the measurement accuracy. For the ECE R49 emissions, the same good overall level of engine out emissions was observed. The individual emission components are compared in fig. A2 and vary within the expected test-to-test variability of single test results.

It can be summarized that the use of TOHO 9000 did not influence engine performance and emission.
The self-governed low idle speed of the engine was identical.

3.2. Endurance Test Procedure

The engine test procedure used for the project is the 500 hours MAN test cycle, as shown in fig. Dl.

This procedure was run 2 ‘/2 times so that a total endurance test running time of 1250 hours was accumulated, which correlates to approximately 100.000 km of vehicle operation.
Fig. D2 gives an overview of the test sequence carried out at AVL during the subject project. The lube oil filling volume of the engine is 21.6 liters approximately.

3.3. Chemical Lube Oil Analysis Results of the 1250 Hours Endurance Test with TOHO 9000

3.3.1. General

Before starting the endurance tests, the engine was filled with Rimula I OW/30 containing 15% by weight TOHO 9000 as lube oil. After an oil sample was taken for the oil analysis, the same amount was refilled with fresh lube oil containing 15% by weight TOHO 9000, thereafter the natural engine oil consumption was topped with Rimula I OW/30 without TOHO 9000, see table 1.

Table 1: Oil Additions

The oil analysis was analysis out with oil samples taken after 0.5, 50, 100 ... 1250 hours engine
running time. Viscosity at 40 and 100 0C, TBN, Insoluble's and wear metals were measured with
Rimula TX I OW/30 + TOHO 9000 oil samples by AVL and Liebherr. Results with Rimula TX
15W/40 oil samples without TOHO 9000 measured by Liebherr are also included in the figures.

3.3.2. Viscosity, Insoluble's and Dispersant Efficiency

Adding TOHO 9000 to Rimula TX I 0W30 results in a viscosity increase to a SAE I 0W50 class and in a drop with a short running time of 50 hours to a SAE 1 0W40 class.

AVL’s and LicbhcIT’s results of viscosity at both temperatures (40 0C/fig. B1 and 100 0C/fig. B2) show this significant decrease from zero to 50 hours running time and a very small further decrease up to Ca. 400 hours running time. From 400 hours running time, a slight viscosity increase in both temperatures appears, the lube oil class is still a SAE I 0W40 class. (Note: The engine oil consumption was compensated with a SAE 10W30 lube oil without TOHO. Nevertheless, the measured viscosity was a SAE I 0W40 oil.)

A completely contrary view is seen in the Liebherr results for the I 5W/40 lube oil without TOHO, where a relatively strong increase in viscosity is seen for the whole time period up to 500 hours running time.

However, a viscosity decrease during the first 50 hours running time can be explained either by an oil dilution with fuel or by the shearing of high molecular compounds to lower molecular ones, but we are not familiar if TOHO 9000 contains high molecular compounds. In order to demonstrate a possible oil dilution, the boiling point distribution of samples was measured by simulated distillation in gas chromatography. No oil dilution with the fuel was detected but a depletion of TOHO 9000 or some compounds of TOHO 9000 as demonstrated in fig. B3. On the other hand, a more or less stable viscosity increase with running time as seen with the standard Rimula TX15W/40 lube oil in figs. B1 and B2 has never been observed at AVL to date. A viscosity increase in diesel engine oils is normally seen if the insoluble content of the oil amounts to 2% and more according to AVL’s experience, and this can be confirmed by the insoluble slopes in fig. B4.

The Insoluble's were measured by infrared spectrometer (JR). By the way, the IR-spectra show a reduction of absorbence frequency at ca. 1740 cm’ wave number (— 5.75 pm) caused by the topping up with lube oil without TOHO and/or by a degradation of compounds containing C = 0 groups. The measured peak minima are shown in fig. B5. The C = 0 degradation became larger and larger and was no longer measurable at running times of more than 500 hours. Carbonyl (C 0) compounds are used as dispersant additives in some lube oil formulations, but may also contribute to TOHO 9000. However, as shown by the drop tests (fig. B6), the dispersant activity of the lube oil containing TOHO 9000 is still excellent after 1250 hrs. engine running time.

3.3.3. TBN
The total base number (TBN) was measured according to ASTM-D-2896 - the perchloric acid procedure - by Liebherr and AVL as well as to ASTM-D-664 - the hydrochloric acid procedure -by AVL only. fig. B7.

Normally, both methods yield the same TBN value for fresh oils, but show different diagrams
over running time (which means increasing oil aging). While TBN values measured by ASTM-D-664 decrease over running time - due to neutralization of strong acids formed during combustion
- an TBN increase measured by ASTM-D-2896 can sometimes be observed - an oxidation of
wear metals occurs by perchloiic acid.

Fig. B7 shows the same TBN number of Rimula 1 5W/40 without TOHO (Licbherr ASTM-D-2896) and I 0W130 lube oil with TOHO (AVL ASTM-D-664). In case of the ASTM-D-2896 measurements of the I OW/30 lube oil with TOHO 9000. AVL and Licbhen found higher TBN numbers for the fresh oil compared to the ASTM-D-664 procedure. but both methods gave the same TBN number in fresh oils without TOHO 9000 when measured in the AVL lab.

However, the ASTM-D-664 procedure shows an unusually flat TBN depletion up to around 500 hours and a relatively stable slope with further running time, but in any case, the TBN degradation is unusually low (also see fig. C13) and no problems even after 1250 hours endurance testing are indicated.

3.3.4. Wear Metals
Wear metals were measured by atomic emission spectrometer in ppm per sample. When topping up, the ppm value is lowered, but the real wear must more or less show a constant increase with running time for given driving conditions. Therefore, the wear is calculated in mg out of the measured ppm value as if no lube oil is consumed by the engine and no topping up has taken place.

After an initial increase, the ppm iron for example seems to be constant by around 80 ppm after ca 500 hours running time (fig. B8). Compared to this, the mg iron is approx. linearly increased with running time (fig. B9) and this means the real wear. The wear rates of iron up to 500 hours running time is comparable for all lube oils, therefore no advantage of TOHO 9000 was found. For copper, the ppm reading in fig. B10 and the calculated mg in fig. B11 showed no linear increased in mg and this indicates a damage, in this case caused by an experimental bushing of the injection pump drive gear. The slopes of all other metals in mg vs. running time were found linear and do not indicate any problems (also see fig. C11).

3.4. Visual Inspection of the Main Engine Components after the 1250 Hours Test with TOHO 9000

After the endurance test run, the engine was disassembled for a visual inspection of the main engine components. This work was done in close cooperation with the engine manufacturer to rely on his experience with engines of the same type running the same endurance test cycle.

Fig. El gives a summary of the assessment of the main engine components such as valves, intake and exhaust ports and manifolds and pistons in order to quantity~’ the visual impression of the buildup of carbon deposits.

The engine run after 1250 hours with TOHO is judged in the right column with a total of 8 points (minimum and thus best results possible is 7 points).

The visual condition of the main engine parts is illustrated in figs. E2,E3,E4,E5,E6,E7,E8,E9, featuring photographs of the original assessment report of the engine manufacturer.

The visual inspection of the main engine pails can be summarized as follows:

It can be concluded that the visual condition of the engine after 1250 running hours with TOHO concerning visual wear and buildup of deposits is equal or better compared to the engine run without an oil change for 500 hours using standard Rimula TXI 5W40 lube oil w/o TOHO.

A comparable engine run over 500 hours with the recommended oil change after 250 hours has been judged to be only marginally better.

3.5. Further Endurance Test Results

Full load performance and emissions versus running time

The engine full load performance and emission status of the engine was regularly checked during the 1250 hours of the endurance test run. Fig. C1 shows the comparison of the engine full load performance before the endurance test and after 1250 hours. A summary of the maximum power

of the engine versus the endurance test time is given in fig. C7. Figs. C2,C3,C4,C5,C6 compare the full load performance of the engine and Fig. C8 the emissions in the ECE R49 cycle in steps of 250 hours.

None of these results indicated any abnormal engine behavior.

As no statistically valid scatter band of results obtained on the same engine type running the same cycle and duration without using TOHO is available, the data cannot be correlated to the use of
TOHO 9000.

Blowby versus running time

The engine blowby, the gas leaking mainly around the piston rings into the crank case is shown in figs. C9 and C1O for three different engine speeds at full load conditions.

After refilling the engine with the mixture of standard oil plus TOHO 9000, the blowby dropped by 5 to 8% within the first 6 running hours when compared to the results when using standard I 5W40 and I 0W30 lube oils.

These results indicate a positive effect of TOHO 9000 on the sealing capability of the piston ring - cylinder liner area.

Wear metals versus running time

Figs. C11 and C12.

The wear metals found in the lube oil show a similar trend for the endurance test engine using TOHO 9000 and the comparison engine run at LMB without TOHO as shown in fig. C12. In this graph the LMB-analysis results by VERNOLAB/France are cross plotted

No indication for a change of the engine wear when using TOHO 9000 was found.

A very linear trend of the engine wear versus the test period indicates no problem on any main engine component.

The increase of copper after about 800 running hours is due to higher wear on one experimental part of the engine fuel injection pump drive and is thus not to be correlated with the use of TOHO (also see chapter 3.3.4).

Comparison of TBN

Fig. C13 shows the degradation of the total base number of the lube oil of the endurance test with TOHO in comparison with the usually experienced degradation of standard oils. Although this comparison is not scientifically correct because it is based on different engines (swept volume 3 to 12 liters) and test cycles (full load cycle, thermo shock cycle), the general trend of an unusually low degradation of TBN can be illustrated.

Oil consumption

The oil consumption of the engine was monitored during the whole test period and is presented in detail in figs. C14,C15,C16,C17,C18.

Fig. C17 shows the trend of the rated power lube oil consumption in terms of (g/h) versus the endurance test running time.

A dramatically increased oil consumption was observed at approximately 600 hours whilst after
750 hours the oil consumption improved continuously and at 1250 hours the level even nearly
reached the initial values again.

The reason is unknown, moreover at the same time also the engine full load smoke and fuel consumption as well as the engine R49 emission results deteriorated simultaneously and improved again later on.

As shown in figs. C14,C15,C16, the natural lube oil consumption of the engine over the 1250 hours endurance test amounted to 63.5 liters, which is approximately 3 times the total oil filling volume of the engine 21.6L).

For fig. 18, showing the engine map lube oil consumption, it has to be mentioned that the measurement was, unfortunately, taken at the time of the highest lube oil consumption, but no other time window was available because of the tight schedule.

The map oil consumption was measured using AVL’s oil consumption meter 403S.

In any way, the lube oil consumption results too cannot be correlated to the use of TOHO 9000 because no comparison data (statistical scatter band) of the same engine type operated without using TOHO along the same cycle and for the same running period is available.