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These recommendations are subject to change without notice. Consult your local Cat dealer for the most up to date recommendations. |
Cat has developed a maintenance management tool that evaluates oil degradation and detects the early signs of wear on internal components. The Cat tool for oil analysis is called S·O·S oil analysis and the tool is part of the S·O·S Services program. S·O·S oil analysis divides oil analysis into four categories:
- Component wear rate
- Oil condition
- Oil contamination
- Oil identification
Component Wear Rate analysis evaluates the wear that is taking place inside the lubricated compartment. The S·O·S Services analyst uses the results of elemental analysis and particle count tests to evaluate the wear. Trend analysis and proprietary wear tables are then used to determine if wear rates are normal or abnormal.
Oil Condition analysis is used to determine if the oil has degraded. Tests are done to look at the oxidation, sulfation, and viscosity of the oil. The S·O·S Services analyst uses established guidelines or trend analysis to determine if the oil has reached the useful life limit.
Oil Contamination tests are performed to determine if anything harmful has entered the oil. This analysis relies on the results from the following tests: elemental analysis, soot, particle count, fuel dilution, water, and glycol. The S·O·S Services program has guidelines for the level of contamination that are allowed in Cat engines.
Oil Identification is another important part of the S·O·S oil analysis program. The wrong oil in an engine can severely damage major components. The S·O·S Services analyst uses elemental analysis and viscosity results to identify key characteristics of the oils.
These four types of analysis are used to monitor the condition of your equipment, and to help you identify potential problems. A properly administered S·O·S Services oil analysis program will reduce repair costs and the program will lessen the impact of downtime.
The S·O·S oil analysis program uses a wide range of tests to determine the condition of the oil and the lubricated compartment.
Guidelines that are based on experience and a correlation to failures have been established for these tests. See the following chart for the guidelines. Exceeding one or more of these guidelines could indicate serious fluid degradation or a pending component failure. A trained person at your Cat dealership should make the final analysis.
Oil analysis is one of the diagnostic tools to determine engine health. Oils that are within the limits given by the guidelines may not indicate all engine health issues. Under certain conditions, including but not limited to severe operating conditions, oils that are within the limits given by the guidelines may require changing early.
Note: Cooling system problems will also reduce the life of engines. S·O·S coolant analysis and S·O·S oil analysis provide a complete and accurate method for monitoring the health of all engine systems. Refer to the S·O·S Services coolant analysis information in this Special Publication. A properly administered S·O·S Services program will reduce repair costs and lessen the impact of downtime.
Refer to the “Contamination Control” article in this Special Publication for recommended fluid cleanliness targets.
| S·O·S Oil Analysis Guidelines | |
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| Test Parameter | Guideline |
| Oxidation | (1) |
| Soot | (1) |
| Sulfation | (1) |
| Wear Metals | Trend Analysis and Cat Wear Table(1) norms |
| Water | 0.5% maximum |
| Glycol | 0% |
| Fuel Dilution | based on viscosity(1) and GC(2) fuel dilution in excess of 4% |
| Viscosity "ASTM D445" measured at |
+/-3 centistoke (cSt) change from new oil viscosity. |
| (1) | Acceptable values for these parameters are proprietary to the S·O·S oil analysis program. |
| (2) | Gas Chromatograph |
Note: Most oil analysis programs do not detect larger particles in the oil sample. Some failure modes only produce larger particles. Oil analysis alone will not always detect an impending failure. Oil filters should be sectioned and inspected for the presence of visible particles.
The engine oil consumption must be measured and recorded. A significant increase in oil consumption can indicate a problem with cylinder pack deposits or components. Additionally, oil additions dilute wear metals and other contaminants. Oil analysis results may become inaccurate.
Consult your Cat dealer for complete information and assistance about the S·O·S oil analysis program.
Before you obtain an S·O·S oil sample, operate the engine until the oil is warm and the oil is circulated. Then obtain the S·O·S oil sample.
In order to obtain a good oil sample, do not take the oil sample from the drain stream. The drain stream method can allow a stream of dirty oil from the bottom of the compartment to contaminate the sample. Likewise, never dip an oil sample from an oil container or pour a sample from a used filter.
There are two acceptable ways to obtain S·O·S oil samples. The following methods are listed in the order that is preferred:
- Use an in-line sampling valve on the pressurized oil manifold.
- Use a sampling gun (vacuum pump) that is inserted into the sump.
Use of the in-line sampling valve is the preferred method. This method provides samples that are less likely to be contaminated. Whenever you obtain the samples, obtain the samples from the same point. The samples will be more representative of the oil that is in the system.
Normally, the oil sample is taken at low idle. If the flow rate is too low, increase engine speed to high idle in order to obtain the oil sample.
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Do not use the same vacuum sampling pump for extracting oil samples that is used for extracting coolant samples. A small residue of either type sample may remain in the pump and may cause a false positive analysis for the sample being taken. Always use a separate pump for oil sampling and a separate pump for coolant sampling. Failure to do so may cause a false analysis which could lead to customer and dealer concerns. |
Take the oil samples as close as possible to the standard intervals. In order to receive the full value from S·O·S oil analysis, establish a consistent trend of data. In order to establish a pertinent history of data, perform consistent oil samplings that are evenly spaced.
Recommended interval for engine oil samples is given in Table 2. A 250 hour sampling interval can provide a timely indication of oil contamination and oil degradation.
Measure and record engine oil consumption in order to allow accurate oil analysis. Oil additions during the sampling interval dilute wear metals and other contaminants.
| S·O·S Oil Sampling Interval for Engine crankcase | |
|---|---|
| Recommended Interval (1)(2) | Oil Type |
| Every 250 Service Hours | Cat DEO
Cat DEO-ULS |
| (1) | Severe applications may require a more frequent oil sampling interval. |
| (2) | Under certain conditions, the Cat dealer or the Operation and Maintenance Manual may allow a longer interval between oil samplings. |
Note: Refer to the Operation and Maintenance Manual for your engine for recommended oil drain intervals.
Consult your Cat dealer for complete information and assistance in order to establish an S·O·S Services program for your engine.
More Frequent S·O·S Sampling Improves Life Cycle Management
Traditionally, the suggested S·O·S sampling intervals for diesel engines have been at 250 hours. However in severe applications, more frequent oil sampling is recommended. Severe service for lubricated compartments occurs at high loads, in high temperatures, and in dusty conditions. If any of these conditions or other severe service indicators exist, sample the engine oil at 125 hour intervals. These additional samples will increase the chance of detecting a potential failure.
Determining Optimum Oil Change Intervals
Sampling the engine oil at every 125 hours provides information for oil condition and for oil performance. This information is used to determine the optimum usable life of a particular oil. Also, more points of data will allow closer monitoring of component wear rates. Close monitoring also allows you to obtain the maximum use of the oil. For detailed information on optimizing oil change intervals, consult your Cat dealer.
This Special Publication does not address recommended oil drain intervals. Refer to your engine Operation and Maintenance Manual, and consult your Cat dealer for additional guidance, including but not limited to guidance on establishing optimized and/or acceptable oil drain intervals.
Note: The use of Cat S·O·S Services oil analysis helps environmental sustainability as the best way to optimize oil life. S·O·S Services will help engines reach expected life. Consult your Cat dealer regarding the testing required to establish a safe, optimized oil drain interval.
Standard oil drain intervals as published in engine Operation and Maintenance Manual are for typical applications:
- Using recommended oils
- Using good fuel
- Using recommended filters
- Using industry standard good maintenance practices
- Following maintenance intervals as published in engine Operation and Maintenance Manual
More severe applications may require shortened oil drain intervals, while less severe applications may allow for longer than standard oil drain intervals. High load factors (above 75%), particularly with high sulfur fuels, can contribute significantly to reducing oil drain intervals below standard oil drain intervals.
Consult your Cat dealer regarding the testing that is required in establishing oil drain intervals that are optimized for your application.
In order to help protect your engine, and help optimize oil drain intervals for engine applications and duty cycles, useCat S·O·S Services oil analysis as follows:
- Recommended as a standard practice
- Recommended in order to determine oil drain intervals when using fuel with sulfur levels between 0.05% (500 ppm) and 0.5% (5000 ppm)
- Required in order to determine oil drain intervals when using fuel with sulfur levels that are above 0.5% (5000 ppm)
Note: Engine operating conditions play a key role in determining the effect that fuel sulfur will have on engine deposits and on engine wear. Consult your Cat dealer for guidance when fuel sulfur levels are above 0.1% (1000 ppm).
Increasing the Oil Change Interval
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Refer to the Operation and Maintenance Manual, "Maintenance Interval Schedule" for the proper oil drain interval of your engine. |
The time between oil changes can only be increased under the following conditions:
- The results of the S·O·S oil analysis indicate that the oil has not deteriorated and/or has high contamination level as identified by S.O.S analysis.
- The trend lines of the S·O·S Services oil analysis program indicate a constant slope that is stable.
- No apparent engine health issues.
- Occasional inspection of engine components does not show wear, corrosion, or other issues of various engine components.
- Occasional inspection of the oil pan or engine components does not show the formation of sludge or unusual deposits.
- Engines operating under severe conditions as defined in the engine Owning and Operating Manual are generally not recommended to extend the oil drain intervals.
The maximum increment for increasing the oil change interval is 250 service hours. Illustration 1 is a graphic representation of adjusting the oil change interval.
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| Illustration 1 | g00585368 |
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(x) Numbers of oil changes
(y) Service hours | |
In Illustration 1, the initial oil change was performed after 1000 service hours. The interval was increased in 250 hour increments. At the fourth oil change interval, the oil had deteriorated and/or has high contamination level as identified by S.O.S analysis after 1750 service hours. Therefore, the interval was reduced to 1500 service hours. The results of the oil analysis are acceptable when the oil was used for 1500 service hours.
Follow all the recommendations and follow proper procedure provided in this Special Publication to extend the oil change interval. For applications that are extending the oil drain interval significantly or that are under severe operation conditions, it is recommended to inspect the following components once per year in order to ensure that the wear rates are within specifications: camshaft segments, connecting rod bearings, cylinder liners, main bearings and pistons.
If SOS oil analysis and other factors allow, maximum oil service life for diesel fueled engines is 3000 hours. Maximum oil service life for heavy fuel oil fueled engines is 2000 hours. Refer to the information provided in this S·O·S article for details.