1990/05/28 Caterpillar

Caterpillar has received a number of inquiries regarding a clarification of the oil recommendations for 3600 Family Engines.

Caterpillar Scheduled Oil Sampling is highly recommended for determining oil change intervals on the 3600 Engine. This article provides guidance on discussing this subject with dealers and users.

Engine oil performs several basic functions in order to provide adequate lubrication. Oil works to keep the engine clean and free from rust and corrosion. It acts as a coolant, and it provides an oil film cushion that keeps metal-to-metal contact to a minimum, thereby reducing friction and wear. These are only the basic functions of oil It is the particular demands of a given application and the special conditions under which an oil is used which largely determine the numerous additional functions it must perform. The selection of the correct oil for 3600 Engines is vital.

The selection of suitable lubricating oil should be given careful consideration, taking into account the quality of the available diesel fuel. The additives in the oil play a very important role. The final performance characteristics of the oil depend upon the base oil and the additive used. The amount or type of additives used will vary according to the properties of the base oil and the environment in which the oil will function.

Maximum engine life and performance can be expected to be achieved on the 3600 Family Engines when the correct engine oil is used. In reviewing engine oils available today, there are significant variations in the quality and performance characteristics of these oils. Caterpillar has done significant research and development work in determining oil requirements for the Family of 3600 Engines.

There are a number of oils on the market today that may qualify for usage in the 3600 Family of Engines. Caterpillar does not recommend lubrication oils by brand name with the exception of Caterpillar branded oils. Caterpillar dealers will work with customers to establish a local source of satisfactory lubrication oil, utilizing present suppliers whenever possible.

Recommendation

Caterpillar has had experience with "Cat Diesel Engine Oil", which is available from Caterpillar Dealers and recommends "Cat Diesel Engine Oil" SAE grade 40 for usage in the 3600 Family of Engines.

There are three areas to consider when selecting oil for the 3600 Family of Engines.

Lubricant Performance

Lubricant Viscosity

Lubricant Total Base Number (TBN)

Lubricant Performance

Minimum API classification of CD or MIL-L2104D plus an acceptable induction time on the deposit formation test (Caterpillar micro oxidation test).

CE is acceptable if it passes the deposit formation test.

CD is acceptable if it passes the deposit formation test.

CD2 is acceptable if it passes the deposit formation test.

CC is not acceptable for use in Caterpillar 3600 Family of Engines.

The deposit formation test must be performed on an oil sample from each oil source or supplier. The deposit formation test can be run at independent labs that have equipment and procedures. Three companies which perform deposit formation tests are listed below. Contact them or similar labs for current fees and capabilities.

Chart A summarizes the interpretation of the micro-oxidation test.

1. Scheduled Oil Sampling (S·O·S) (with infrared analysis), oil consumption, and crankcase pressure must be analyzed every 250 hours.

2. A maximum of 1,500 hours between oil changes for the first 3,000 hours.

3. If no oil-related problems are encountered for the first 3,000 hours of operation, then the oil is considered acceptable for that particular application and associated load factor. Oil change periods can then be determined by S·O·S (with infrared) methods at 250-hour intervals.

Lubricant Viscosity

The primary recommendation for the 3600 Engine is an SAE 40 grade oil. SAE 30 grade and multigrade oils can be used according to Chart B.

Lubricant TBN

Minimum initial new oil TBN should equal 20 times the fuel sulphur level as measured by ASTM D-2896. For fuels with less than 0.5% sulphur, the minimum TBN value is 10.

Lubrication Oil Change Period

In order to achieve the maximum usable life from the engine oil, and at the same time, provide the optimum lubrication qualities to the engine, Caterpillar recommends a regular Scheduled Oil Sampling program that is available through the Caterpillar worldwide network of dealers.

Caterpillar's Scheduled Oil Sampling is a maintenance tool for all Caterpillar Engines and Machines. It is basic, modern, preventive maintenance.

Caterpillar's S·O·S includes a series of three types of diagnostic tests:

1. Wear Analysis

2. Chemical and Physical Testing

3. Oil Condition Analysis

1. Wear analysis is performed with an atomic absorption spectrophotometer. After three oil samples are taken, trend lines for the various wear elements can be established. Impending failures can be identified when trend lines deviate from the established norm.

2. Chemical and physical tests are used to evaluate the following:

Viscosity (ASTM D 445 @ 100°C or 212°F) - oil should be changed when the used oil viscosity is 3 cSt above new oil viscosity, measured at 100°C (212°F).

TBN (ASTM D 2896) - oil should be changed when the TBN reaches 50% of new oil TBN. (Based on the fact that the oil change does not occur at the time the oil sample is taken and further TBN depletion happens before removing the used oil.)

Insolubles (ASTM D 893 or infrared scan) - oil should be changed when the insolubles reach the following levels:

Insoluble Pentane 3% Maximum

Insoluble Toluene 2% Maximum

Water in oil ("sputter test") - oil is placed on a 110° C (230° F) hot plate. Bubbles formed during this procedure are compared to oils with a known water content. If 0.5% water is detected in the used oil, then the oil should be changed.

Glycol (ASTM D 2982 procedure B) - no glycol is allowed. Change oil if glycol is detected in the used oil sample.

Fuel dilution (ASTM D 3828 procedure A) - if 3 to 4% fuel dilution is detected in the used oil, then the oil should be changed.

3. Oil condition is also monitored by infrared (IR) analysis. Infrared is used to measure soot, sulfur, oxidation, and nitration products. Trend lines can also be established from the IR scans. Deviations from these trends can be used to determine oil change period or to determine an engine problem.

Oil change periods are established by trends that are formed by oil analysis results up to the time the condemning limits are reached. The 3600 Family of Engines are to have oil samples drawn off at 250-hour intervals. This sampling interval should be maintained during the operating life of the engine. Oil analysis results combined with maintenance records can give information about the condition of the engine.

The source for the best information on oil sampling is a Caterpillar dealer with an oil sampling program. Oil samples should be coordinated through the local Caterpillar dealer.

Oil Change Period Without S·O·S

If S·O·S type analysis is not available, use Chart C for oil change period.

Basic Maintenance of the Lubrication System

Probably the most important step toward preventing oil-related failures is to be on the alert as a matter of routine. Specifically, this means being sensitive to the early signs of trouble. One way to do this is with a very basic check for obvious warning signals. When a check is made, it should include these key elements.

1. An external check of the engine for any obvious signs of leakage.

2. A check of the oil pressure. A change here could indicate anything from a faulty oil pump to a stuck pressure relief valve.

3. A check of the oil level. A low oil level could be caused by excessive consumption, leakage, or failure of oil lines.

4. Keep records of oil consumption and review these records regularly as part of a good preventive maintenance program.

Summary

You are directly responsible for your engine's performance. You can lessen the chances of oil related failures by taking the initiative to protect your engine.

Select the correct quality and viscosity oil for the application.

Follow recommended oil and filter change intervals.

Practice good maintenance procedures.

Pay attention to S·O·S results.