PLUNGER 3T0647 - Caterpillar

On-highway Engine: C13 (S/N: LEE1-UP) C15 (S/N: SDP1-UP; B5R1-UP)Introduction
Before you perform any procedure in this Special Instruction, read the information and understand the information that is contained in this instruction.This special instruction includes the recommended methods for determining fuel dilution of the engine oil. Additionally, the probable causes and the recommendation for correcting the fuel dilution are provided.Recommended Actions
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 fuel that remains in the oil is less volatile.A closed cup flash test is sometimes used to detect fuel dilution by measuring the volatile parts of the fuel that are remaining in the oil. Detecting less volatile components of the fuel that are left behind in the sump is more difficult and the accuracy of the flash test is reduced significantly.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 viscosityA significant level of fuel dilution reduces oil viscosity. Caterpillar SOS service's recommends a viscosity test for all diesel engine oils. The viscosity test must measure the kinematic oil viscosity in centistrokes (cSt) at 100° C (212° F). The result of the viscosity test is compared to SOS service's guidelines. A gas chromatograph is used in order to test for fuel dilution if the viscosity of the oil is below the guideline's value. The gas chromatograph is designed to measure fuel dilution in crankcase oils. The gas chromatograph can identify the small chemical differences between diesel fuel and lubricating oil. A gas chromatograph is used to measure fuel dilution at a regional Caterpillar SOS lab. Some Caterpillar dealers also use a gas chromatograph. Even though the gas chromatograph provides a more accurate measure of fuel dilution the oil's viscosity should determine future actions and engine maintenance.Fuel dilution that is greater than four percent will usually cause viscosity that is less than the specified viscosity grade. For example, 15W-40 oil with four percent fuel dilution will have a viscosity of less than 12.5 cSt. The level of fuel dilution is higher in on-highway engines that are mandated for 2007 emissions requirements. The guidelines for fuel dilution have been changed in order to address the trends. 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     Oil Viscosity at (100 °C)     Percentage of fuel dilution     Action    
0W-40
5W-40
10W-40
15W-40
20W-40     Greater than 11.5 cSt     Less than 6     No Action is Required.    
Greater than 11.5 cSt Greater than 6     The oil must be sampled at the