CYLINDER BLOCK ASSEMBLY 7M8650 - Caterpillar

Table 3
Test 797F Engine Not-to-Exceed Recommendations
Iron (Fe) 80 ppm
Lead (Pb) 4 ppm
Soot 90 UFM
Oxidation New Oil Oxidation Plus 20 UFM
Viscosity New Oil Viscosity Plus 3 cSt at 100C The plots below (Illustration 5) show the baseline results from a truck that was equipped with the Cat COF and the Cu/Ni oil cooler. Three oil drains were completed at approximately 500-hours. The key test results were plotted and regression lines were created. The dotted line on the plots represents the Not-to-Exceed recommendations. The regression line was extended to about 1.5 times the baseline oil drain. As the plots show, none of the extended regression lines exceed the recommended values in Table 3.
Illustration 5 g06219992The next step is to select the target oil drain for the extension. The target oil drain should be approximately 1.5 times the baseline oil drain. Since the baseline oil drains were in the 500 to 600-hour range, the target oil drain was set at 800-hours.
Illustration 6 g06221980This next set of plots in Illustration 6 show the results from four extended oil drains. The last oil drain was at 868 hours. The key oil sample results were still linear out to almost 900 oil hours. Also, these key results did not reach the Not-to-Exceed recommended values. This truck thereby demonstrated acceptable 1000-hour oil drains. At this point, oil sampling can also be reduced to 250-hour intervals. This 1000-hour oil drain could be applied to other 797F trucks in the fleet.
Illustration 7 g06221983A Note of CautionDo not skip this verification program and go directly to the target oil drain. This verification program is set up with more frequent oil sampling to provide safe operation. This next example shows how quickly an oil deterioration problem can occur. The engine in this example is a 3516B HD. The engine was run on a dyno at a high load factor. The key oil sample results looked good, out to 250 oil hours, see Illustration 7. The regression lines were linear and the values were low.
Illustration 8 g06221985The oil was not changed, and the test engine was run for an additional 138 hours, shown in Illustration 8. At 300 hours on the oil, there was a small increase in (Pb). The other key results stayed on a linear trend. The small increase in (Pb) was not in itself significant. However, the next sample at 350 oil hours showed a much larger increase in (Pb). Therefore, the (Pb) increase at 300 hours was an early signal that the oil was degrading. Also by 350 oil hours, the Iron (Fe) and Oxidation had increased significantly. This action verified that the oil had significantly degraded and become corrosive. The test was ended at 388 oil hours.
Illustration 9 g06221988The test was concluded before a catastrophic engine failure occurred. However, there was damage done by the degraded oil. The main bearings in Illustration 9 were removed from the test engine. Severe overlay corrosion removed much of the overlay from these bearings. Bearing overlay corrosion is not the only failure mode which