DRIVE GP-SWING 4567223 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Problem
Diesel engines with fuel injectors will have some degree of fuel dilution. Diesel fuel lubricates the plunger and barrel assemblies that are part of the fuel injectors. Since diesel fuel is used to lubricate the upper end of the plunger and barrel assemblies, a small amount of fuel will leak into the crankcase oil. The amount of fuel dilution depends on the condition of the fuel injectors and on the load on the engine. Use the following information to determine whether fuel dilution has reached an unacceptable level. If you find an unacceptable level of fuel dilution, reference the engine's Troubleshooting manual.Solution
Measuring Fuel Dilution
Diesel fuel is chemically similar to the lubricants that are used in diesel engines. A slow fuel leak will blend the fuel into the oil. Normal operating temperatures may cause volatile parts of the fuel to vaporize. The remaining fuel is less volatile. A closed cup flash test is sometimes used to detect fuel dilution. The flash test is designed to measure the volatile parts of the fuel that are remaining in the oil. Detecting less volatile fuel is difficult. This reduces the accuracy of the flash test.Since the flash test does not accurately detect fuel dilution, do not use the flash test as the only measure of fuel dilution. Instead, verify the dilution by the following methods:
Gas chromatograph fuel dilution test
Oil viscosityUse both the gas chromatograph fuel dilution test and the measure of the oil viscosity to provide a more accurate result.The gas chromatograph method is designed to measure fuel dilution in crankcase oils. The gas chromatograph instrument can identify the small chemical differences between diesel fuel and lubricating oil. A gas chromatograph is used to measure fuel dilution at all Caterpillar regional S O S Service labs. Some Caterpillar dealers also use a gas chromatograph. Even though the gas chromatograph provides a more accurate measure of fuel dilution, always verify the results with the viscosity test.A significant level of fuel dilution reduces oil viscosity. If an unacceptable level of fuel dilution is suspected, the kinematic viscosity of the oil must be measured.Fuel dilution that is greater than four percent will usually cause viscosity that is less than the specified viscosity grade. If the oil is still within the specified viscosity grade, it is likely that fuel dilution has not reached an unacceptable level. Use the following chart to determine if viscosity has reached the minimum acceptable level. The guidelines of viscosity in the chart are slightly less than the limits of the SAE viscosity grades. However, these guidelines still provide adequate engine protection.
Table 1
Viscosity Grade     Minimum Oil Viscosity at 100 °C with Fuel Dilution Greater Than 4% as Measured by a Gas Chromatograph     Action    
0W-40
5W-40
10W-40
15W-40     12.0 cSt     Investigate the cause of fuel dilution or reduce the engine oil change interval. Refer