Series 638 – Section 5.2 Lubricating Oil

Section 5.2
Lubricating Oil

Hundreds of commercial oils are marketed today, but labeling terminology differs among suppliers and can be confusing. Some marketers may claim that their lubricant is suitable for all makes of diesel engines and may list engine makes and types, including Detroit Diesel, on their containers. Such claims by themselves are insufficient as a method of lubricant selection for the Turbotronic 638 engines. ‪

The proper lubricating oil for the Turbotronic 638 engines is selected based on SAE Viscosity Grade and API (American Petroleum Institute) Service Designation. Both of these properties are displayed in the API symbol (see Figure "API Symbol" ) which is illustrated within the specific requirements.‪

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Figure 1. API Symbol

At ambient temperatures below -20 ° C (-4 ° F) when sufficient starter speed cannot be achieved with SAE 15W-40 oils, the use 5W-X and 10W-X oils may be used to improve startability provided they are API CG-4 and have demonstrated field performance in DDC engines. These oils must posses a HT/HS of 3.7 minimum.‪

Lubricants meeting these criteria have provided maximum engine life when used in conjunction with specified oil drain and filter maintenance schedules. Only oils licensed by API may used in the Turbotronic 638 engines.‪

The API CG-4 performance category was introduced in January 1995. Lubricants meeting CG-4 criteria are intended for use primarily with low (0.05%) sulfur fuel. Compared to API CF-4 certified oils, these oils have improved soot and deposit control, in addition to enhanced wear control. API CF-4 oils may be used when CG-4 is not available.‪


Monograde oils should not be used regardless of API Service Classification. Failure to observe this precaution may result in inadequate lubrication and severe engine damage.‪

When the use of high sulfur fuel (greater than 0.5% mass sulfur) is unavoidable, higher alkalinity lubricants are recommended. High sulfur fuels require modification to oil drain intervals.‪

Section 5.2.1
SAE Viscosity Grade

Viscosity is a measure of an oil's ability to flow at various temperatures. The SAE viscosity grade system is defined in SAE Standard J300, which designates a viscosity range with a grade number. Lubricants with two grade numbers separated by a W, such as 15W-40, are classified as multigrade. Those with a single number are monograde. The higher the number, the higher the viscosity.‪

The recommended viscosity grade for the Turbotronic 638 engine is 15W-40 for most ambient conditions. Other viscosity grades such as 5W-40 and 10W-30 may be used to improve low temperature starting. These oils must be API licensed CG-4 service to maintain engine durability and possess a minimum high temperature shear viscosity of 3.7 cp min.‪

Section 5.2.2
Additional Requirements

Although the API designation identifies the minimum desirable performance levels, Detroit Diesel has identified additional properties that further assure the best possible engine lubrication.‪

Refer to "5.2.3 High Temperature/High Shear Viscosity" for high temperature and high shear viscosity requirement.‪

Refer to "5.2.4 API Service Classification" for API Service classification clarification.‪

Refer to "5.2.5 API Symbol" for API Symbol clarification.‪

Refer to "5.2.6 Sulfated Ash and Total Base Number" for sulfated ash and total base number limits.‪

Refer to "5.2.7 Universal Oils" for clarification on universal oil selection.‪

Refer to "5.2.8 Synthetic Oil" for synthetic oil requirements.‪

Refer to "5.2.9 The Use of Supplemental Additives" for the use of supplemental additives.‪

Refer to "5.2.10 Waste Oil Disposal and Rerefined Oils" for waste oil disposal and rerefined oils.‪

Section 5.2.3
High Temperature/High Shear Viscosity

Unlike kinematic viscosity, High Temperature/High Shear (HT/HS) viscosity is measured under conditions similar to those of an operating engine. The test is conducted at 150 ° C under shear stress conditions, similar to those found in thin film lubrication areas, like the piston ring-to-cylinder wall interface. The value obtained indicates the temporary shear stability of the viscosity index improver used in multigrade oils. In 15W-40 grade oils, an HT/HS viscosity below 3.7 centipoise (cP) indicates that the oil will not perform as a 40 grade oil under engine operating conditions.‪

Section 5.2.4
API Service Classification

The American Petroleum Institute (API) has developed a means of classifying lubricants for different engines and applications. The highest performance classifications include API CF, CF-2, CF-4, and CG-4. Detroit Diesel does not recommend the use of older and lower performance classifications, including API CE, CD, CC, and CB. Qualifying tests for these classifications have been discontinued.‪

When multiple API classifications are used, make sure that the classification specified by Detroit Diesel is listed. Oils designated SG or SH are for gasoline engine passenger car applications. Detroit Diesel recommends oils without these designations.‪

Section 5.2.5
API Symbol

Lubricant marketers have adopted a uniform method of displaying the SAE viscosity and API service classification on product containers and in product literature. The three segment donut contains the SAE grade number in the center and the API service classification in the top segment. The lower segment is used to designate the energy conservation status for gasoline engines and has no significance for diesel engines.‪

A marketer is required to license his oil with API in order to display the symbol. Some marketers may indicate that their products meet API requirements. This is not adequate. Although the licensing process cannot guarantee good oil performance, the marketer must be able to produce data to substantiate that their oil meets the service classification. Only oils licensed by API should be used in Detroit Diesel engines.

Section 5.2.6
Sulfated Ash and Total Base Number

Sulfated ash is a lubricant property measured by a laboratory test (ASTM D 874) to determine the potential for formation of metallic ash. The ash residue is related to the oil's additive composition and is significant in predicting lubricants, which may cause valve distress under certain operating conditions. Sulfated ash is related to the Total Base Number (TBN), which measures an oil's alkalinity and ability to neutralize acid using a laboratory test (ASTM D 2896 or D 4739). As TBN increases, sulfated ash also increases to where lubricants with TBNs above 10 will likely have sulfated ash contents above 1.0% mass.‪

Total Base Number is important to deposit control in four-stroke cycle diesel engines and to neutralize the effects of high sulfur fuel in all diesel engines.‪

When the use of oil with high ash content is required, such as with high sulfur fuel, the oil selected should have the highest TBN (D 2896) to Ash (D 874) ratio possible. For example, an oil with a TBN of 10 and an Ash of 1.2% mass is less desirable than an oil with the same TBN and 1.0% Ash. Also refer to "5.2.12 Oil Change Intervals" for change intervals.‪

Section 5.2.7
Universal Oils

Universal Oils are designed for use with both gasoline and diesel engines and provide an operational convenience in mixed engine fleets. These products are identified with combination API category designations such as SG/CF or CG-4/SH. Although such products can be used in the Turbotronic 638 engines (provided they satisfy all Detroit Diesel requirements), their use is not as desirable as lubricants formulated specifically for diesel engines and having the CG-4 designation. When selecting a universal oil, select one with the ” C" category first as this should be primarily intended for diesel service. ‪

Section 5.2.8
Synthetic Oil

Synthetic oils may be used in the Turbotronic 638 engines provided they are API licensed and meet the performance and chemical requirements outlined in this publication. Synthetic oils offer improved low temperature flow properties and high temperature oxidation resistance. They may be marketed in viscosity grades different than those recommended in this publication. These may be used if accompanied by proof of satisfactory field performance.‪

Product information about synthetic oils should be reviewed carefully. To offset their higher cost, synthetic oils are claimed to provide benefits in extended oil drain intervals. Such claims must be substantiated by the oil supplier. Refer to the section on ” Oil Change Intervals."‪

Section 5.2.9
The Use of Supplemental Additives

Lubricants meeting the Detroit Diesel specifications outlined in this publication contain a carefully balanced additive treatment. The use of supplemental additives, such as break-in oils, top oils, graphitizers and friction-reducing compounds, in these fully formulated lubricants are not necessary and can upset the oil's formulation causing a deterioration in performance. These supplemental additives may be marketed as either oil treatments or engine treatments and should not be used in the Turbotronic 638 engines damage resulting from the use of such materials is not covered by your Detroit Diesel Corporation warranty. Detroit Diesel will not provide statements relative to their use beyond this publication. ‪

Section 5.2.10
Waste Oil Disposal and Rerefined Oils

With over one billion gallons of waste oil generated annually in the U.S. alone, disposal of waste oil has become a serious environmental concern. Refining waste oils provides an environmentally viable way of handling this material. Several states have established collection and recycling programs. A few states have also designated used oil as a hazardous waste requiring special handling and disposal. Detroit Diesel favors the recycling of waste oil and permits the use of rerefined oils in all engine product lines, provided the rerefined oil meets the SAE Viscosity and API specifications previously mentioned. ‪

Several processes are used to refine oil. The only true refining process is one which treats the used oil as a crude oil, subjecting it to the same refinery processes normally used for geological crude such as dehydration, vacuum distillation, and hydrogenation. Waste oil provides a more consistent feedstock, compared to the geological crudes that a refinery typically processes. As a result, the finished oil should also be consistent in properties and quality. Unfortunately, this is not the norm. It is the inconsistencies of the processing and product quality which make most users reluctant to utilize rerefined products. ‪

Consideration for the disposal of waste oil should begin when negotiating the purchase of new oil. Oil supplier selection criteria should include a proposal for handling waste oil. It is important to know exactly how the oil will be disposed of since it is the generator, not the hauler, that is ultimately responsible for its proper disposal.‪


Extended skin contact with used motor oil may be harmful and should be avoided.‪

Section 5.2.11
Brand Name Approved Lubricants

Detroit Diesel does not maintain a list of brand name approved products. All lubricants which meet the qualifications listed in this publication will provide satisfactory performance when used in conjunction with the oil drain and filter requirements. To ensure that the lubricant selected meets these qualifications, the customer should make sure that the candidate oil has a current API license number. Although the lubricant supplier should be able to supply this information, it may also be obtained from other sources.‪

Section 5.2.12
Oil Change Intervals

During use, engine lubricating oil undergoes deterioration from combustion by-products and contamination by the engine. Certain components in a lubricant additive package are designed to deplete with use. For this reason, regardless of the oil formulation, regular oil drain intervals are necessary. These intervals may vary in length, depending on engine operation, fuel quality, and lubricant quality. Generally, shorter oil drain intervals extend engine life through prompt replenishment of the protection qualities in the lubricant. Conversely, extending oil drain intervals beyond the useful life of the lubricant can significantly reduce engine durability.‪

The oil drain intervals listed in Table "Maximum Allowable Oil Drain Intervals - Normal Operation with Low Sulfur Fuel" (normal operation with low sulfur fuel) should be considered maximum and should not be exceeded. Always install new engine oil filters when the oil is changed.‪

Service Application

Oil Drain Interval

On-highway Truck‪

6,000 Miles (10,000 km)‪

Table 3. Maximum Allowable Oil Drain Intervals - Normal Operation with Low Sulfur Fuel

Note: Always install a new oil filter when the oil is changed.

Section 5.2.13
Extended Oil Drain Intervals

Some oil companies may promote engine lubricants with a claimed useful life that would allow customers following certain maintenance and operating parameters to elect to extend oil drain intervals beyond the recommended periods. The ability of such lubricants to maintain their protective qualities over a longer period and the acceptability of maintenance and operating parameters must be established by the oil company and the customer. Claims for engine failure attributable to the inadequacy of the lubricant are not covered under the terms of the engine's limited warranty.‪

Section 5.2.14
Using High Sulfur Fuels

Although only diesel fuels containing more than 0.5% sulfur are considered high sulfur fuels, piston ring wear studies indicate that fuels containing more than 0.3% sulfur significantly increase ring face wear rates. See Figure "Effect of Fuel Sulfur Content on Engine Life" .‪

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Figure 2. Effect of Fuel Sulfur Content on Engine Life

High sulfur content forms acid during combustion, particularly during idling and low temperature operation. To minimize the effects of high sulfur content, shorten oil drain intervals. The appropriate oil drain interval may be determined by oil analysis or by using the intervals listed in Table "Maximum Allowable Oil Drain Intervals - Normal Operation with Low Sulfur Fuel" .‪

Section 5.2.15
Used Oil Lubricating Oil Analysis

A used oil analysis program such as the Detroit Diesel's POWER Trac ® oil analysis program is recommended for monitoring crankcase oil in all engines. Oil analysis consists of a series of laboratory tests conducted on the engine lubricant. Most tests reveal conditions of the engine, while some indicate the condition of the lubricant. The "Warning Limits" listed in Table 5-3 shows what each test evaluates. Since an oil analysis cannot completely assess the lubricating oil for continued service, it should not be used to extend oil drain intervals. An oil analysis program with regular sampling is recommended, and the oil should be changed immediately if contamination is present in concentrations exceeding the warning limits listed in Table "Single Sample Used Oil Analysis Warning Limits" .‪



Condition Measured


Viscosity at 405C (745F), cSt % Maximum Increase‪


Engine and Oil‪


Viscosity at 405C (745F), cSt % Maximum Decrease‪


Engine and Oil‪


Carbon, (Soot) Content, TGA Mass % Maximum‪

E 1131 or LEM*‪

Engine Combustion‪


Pentane Insolubles, % Maximum‪

D 893‪

Engine Combustion‪


Total Base Number (TBN) Minimum‪

D 4739‪



Total Base Number (TBN) Minimum‪

D 2896‪



Water, Volume % Maximum‪

D 1744‪



Fuel Volume % Maximum‪

D 3524‪



Glycol Volume. ppm Maximum‪

D 2982‪



Iron, Fe ppm Maximum‪

D 5185‪

Engine Wear‪


Copper, Cu ppm, Maximum (Above Baseline)‪

D 5185‪

Engine Wear‪


Table 4. Single Sample Used Oil Analysis Warning Limits

Note: *SM 1 is a patented soot measurement process by Analysts, Inc.

Note: These limits are intended to be used as guidance when a single oil sample is tested. Actual limits are dependent on engine, application, and oil type. Refer to DDC publication 7SE398 for determining warning limits specific to your application.

Section 5.2.16
Used Lubricating Oil Analysis Warning Limits

Warning Limits are based on a single oil sample taken by an accepted sampling method. These values indicate the need for an immediate oil change, but do not indicate internal engine malfunctions requiring engine teardown.‪

Section 5.2.17
Oil Filter

The oil filter requirement is listed in Table "Lubricating Oil Filter Requirements" .‪

Filter Type

Micron Rating @ 98% Single Pass Efficiency



Table 5. Lubricating Oil Filter Requirements

Series 638 Service Manual - 6SE648
Generated on 10-13-2008

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