United States National Risk Management

Environmental Protection Research Laboratory

Agency Cincinnati, OH 45268

Research and Development EPA/600/SR-96/092 September 1996

Waste Oil Reduction for

Diesel Engines

Project Summary

Todd Sigaty, Carl Reller, and Daniel Middaugh

This project reduced waste oil from

diesel engines at remote sites in Alaska

by extending oil change intervals using bypass filters and a closed-loop

reblending process in connection with

portable field monitors and laboratory

analysis. Incidents of normal and abnormal oil degradation were recorded

and correlated between field and laboratory tests. A quality assurance program evaluated data precision and accuracy.

Waste oil from diesel engines represents the greatest environmental health

problem in Alaska, especially in remote

areas where disposal/recycling options

are nonexistent. Results of this project

showed that small, isolated communities can reduce the amount of waste oil

generated at the source with techniques

that are easy to implement and inexpensive. However, they depend primarily on operator interest in closely monitoring the engine because degradation

levels need to be determined individually for each engine and oil type by

establishing baseline data.

This Project Summary was developed

by EPA’s National Risk Management

Research Laboratory, Cincinnati, OH,

to announce key findings of the research project that is fully documented

in a separate report of the same title

(see Project Report ordering information at back).

Introduction

This study was a cooperative effort between EPA’s National Risk Management

Research Laboratory (NRMRL) and the

Alaska Health Project (AHP), the central

site of the project. The AHP, located in

Anchorage, is a nonprofit organization offering technical assistance on pollution

prevention and waste reduction. The goal

of this project was to test different technologies to reduce waste oil at remote

sites in Alaska.

The generation of energy is critical to

remote villages, marine vessels and military bases throughout Alaska. The use of

diesel generators to provide that energy

results in large quantities of used oil, part

of the more than one billion gallons of

waste oil generated annually in the U.S.

The U.S. Environmental Protection

Agency (EPA) is concerned about the

quantity of waste oil improperly disposed

of each year because of its threat to the

environment and its cost to remediate.

Carefully managed, used oil retains its

economic value, but many small communities have neither the experience nor the

knowledge to evaluate the condition of

used oil or to determine a reasonable

means of recycling. Consequently, much

of the accumulated used oil is transported

many miles at substantial cost, and indiscriminate dumping is common. Current

filtration technology may be able to process used oil on site, providing a recycled oil that meets specifications for

burning. Objectives for this project were

to determine (1) whether engine

manufacturer’s recommendations for oil

change intervals (OCIs) could be increased with field and laboratory measurements of oil degradation; (2) whether

bypass filters are effective in extending

oil drain intervals; (3) whether the

closed-loop process is efficient and affordable in eliminating waste oil; and (4)

whether these technologies can be easily

implemented by small, isolated communi-
2

ties. The project also evaluated whether

technologies for extending oil life would

concentrate polynuclear aromatic hydrocarbons (PAHs) at levels hazardous to

the health of oil handlers.

Procedure

The sites selected for this project were

stationary electric generating plants located

in rural areas ranging from the Arctic north,

through the Aleutian Islands, to the temperate rain forests of Southeastern Alaska.

Other participants were a marine vessel

and a federal hydroelectric facility. Phase

I—extension of oil change intervals using

analysis alone—was conducted over an

11-month period at 13 Alaskan sites on

20 diesel engines ranging from 23 to 3,000

hp. Participants were asked to gradually

extend OCI based on field monitoring and

laboratory analysis alone.

In Phase II—extension of OCIs through

the use of bypass filters—data was compiled from nine diesel engines at four sites.

Filtration is defined for this project as the

physical separation of liquids and solids

by means of centrifuges and media filters,

the two technologies commonly used in

bypass filters. Oil is commonly filtered between oil pump and engine by diverting

100% of the oil through a “full flow” filter

able to remove large particles (greater

than 20 microns). Full flow filters are inefficient at removing liquids (such as water,

unburned fuel or acids) and small metal

contaminants below 20 μm. Bypass filters

remove particles in the below-20-micron

range by intercepting about 10% of the

main flow of oil. The following filter systems were selected for this project based

on product quality and information, experience and cost: Gulf Coast, Spinner,

Purifiner, Harvard and Power Plus. Used

oil samples were taken from the engines

as often as every two days and tested by

the engine operator onsite and by the

project manager at the AHP office. To

monitor oil quality in the field a portable

battery-powered comparative dielectric

analyzer (CDA) was used. This equipment

determines the deterioration in motor oil

from continued use. By measuring any

deviation of the dielectric constant between

fresh and used oil, it indicates the overall

condition of the oil and helps determine

the optimal oil change interval. For this

project, the LubriSensor Model NI-2B was

selected based on its cost, usability and

documentation ability. After each sample

was tested in the field it was sent to Analysts Laboratory in Oakland, CA, for analysis of the physical and chemical properties of the oil. This lab was chosen after a

national search on the basis of its quality

manuals, experience and commercial availability. For this project, Analysts tested

each sample for 21 metals and the total

base number (TBN). TBN is an indicator

of oil buffering quality, i.e., the quantity of

hydrochloric acid, expressed in terms of

the equivalent number of milligrams of

potassium hydroxide required to neutralize all the basic constituents present in a

one-gram sample of oil. The TBN indicates relative change in oil regardless of

color or other properties. This project chose

to analyze TBN and CDA as the best

indicators of oil quality. Lab results were

sent to AHP and then to the engine operator. With every fifth used oil sample, a

quality control sample was sent to the lab.

In Phase III—the elimination of waste

oil through reblending and recycling—a

closed-loop process was used on a stationary engine and a marine engine at two

different sites. The closed-loop process is

one in which the oil is removed from the

engine at a set rate and blended in the

fuel tank at a varied ratio of oil to fuel. In

addition to eliminating the need to dispose of waste oil, the quality of the fuel is

increased. For this project, the Power Plus

Smart Tank Model ED3500S was selected

for the stationary engine; the Volvo MD11C

marine engine used its own blending system constructed onsite. Oil was removed

at the rate of 1.3 oz/engine hr and blended

in the fuel tank at 2% oil : fuel. This

removal rate uses the same amount of oil

as changing the oil once every 150 hr.

Upon good analysis, the removal rate was

reduced by 50% to .65 oz/hr, and the

blend to 1% oil : fuel, a removal rate

equal to changing the oil once every 300

hr.

During the project, the methods or independent variables were oil analysis and

filtration systems. Dependent variables

were oil change intervals and cost. Results from samples collected at each site

were compiled on data sheets and entered into a database. To ensure accuracy, the data were entered twice by two

separate individuals. Each data set was

cross checked for discrepancies. All measurements, data gathering equipment and

data generation activities were routinely

assessed for precision, accuracy, completeness and detection limits.

Results and Discussion

Results of the data were plotted on

graphs; several examples are shown here.

Figure 1 shows the CDA readings against

engine hours on oil for each of the bypass

filters on engine No. 5. A higher CDA

rating can be an indication of possible oil

contamination. The control plot is an extension of oil drain interval without a bypass filter. On this engine the control

samples had lower CDA readings than

samples from the Spinner filter. The

samples from the Purifiner filter had a

lower CDA reading than the Spinner or

control samples. All samples on this engine were able to extend their OCI to over

800 hr without any CDA readings indicating oil contamination. Figure 2 shows CDA

readings against engine hours for the control used-oil samples and the Gulf Coast

used-oil samples on engine No. 8. A higher

CDA reading can be an indication of possible oil contamination. The control plot is

an extension of oil drain interval without a

bypass filter. This figure shows that on

this engine the control samples had lower

CDA readings than the Gulf Coast

samples, but that both sets of used-oil

samples were able to be extended to over

1200 hr without any CDA readings indicating oil contamination. Figure 3 shows

the CDA readings against engine hours

for the control used oil samples and the

1.5% oil : fuel blend samples on the Volvo

MD11C engine within a 95% confidence

level. A higher CDA reading can be an

indication of possible oil contamination.

The control plot is an extension of oil

drain interval without a by-pass filter. The

blend is a closed-loop process where used

oil is blended with incoming fuel. This

figure shows lower CDA ratings than the

control samples on this engine. The blend

samples were extended to over 200 hr

without CDA readings indicating any oil

contamination. (Manufacturer’s recommendation is 50 hr.) The control samples were

able to extend the oil to over 350 hr but

had CDA readings indicating possible oil

contamination. Figure 4 plots the complete range of data points and extends

the data to the point where TBN level

would reach zero on the Volvo MD11C

engine. The figure shows a direct relationship between CDA and TBN readings with

a 95% confidence level extended to over

1000 hr. This ability to predict the TBN

level aids the engine operator because

lab analyses take time and are costly.

Conclusions

This study focused on answering the

objectives stated in the Introduction. The

study finds that:

1. Oil change intervals can be extended

beyond engine manufacturers’ warranty

recommendations without oil degradation. To ensure protection of the engine

while extending the OCI, field monitoring of oil condition is recommended.

CDA data collection is easy, inexpen-
3

2.0

2.5

1.5

1.0

0.5

0 200 400 600 800 1000 1200

Hours on Oil

Spinner

Control

Purifiner

CDA Reading

Figure 1. Bypass filter vs. control samples CAT 3512, engine No. 5.

2.5

3.0

0.5

0.0

0 200 400 800 1000 1200

Hours on Oil

CDA Reading

1.0

1.5

2.0

600 1400

95% Confidence

Gulf Coast

Control

Figure 2. Bypass filter vs. control samples CAT 3516, engine No. 8.
4

3.0

0.5

0 50 100 200 250 300

Hours on Oil

CDA Readings

1.5

2.0

150 350

95% Confidence

Control

1.0

2.5

Blend

 10

0 400 1200 1400 1600

Hours on Oil

CDA Readings

 4

 6

600 2000

95% Confidence

CDA

 1

 7

TBN 2

 3

 5

 8

 9

200 800 1000 1800

 7

 6

 5

 4

 3

 2

 1

 0

Total Base Number

Figure 3. 1.5% oil : fuel blend engine, Volvo MD11C.

Figure 4. Control extended to zero TBN engine, Volvo MD11C.
5

sive and a good indicator of oil degradation. There is a consistent relation

between CDA readings and TBN levels

in measuring oil degradation. However,

each engine and situation is unique.

Therefore, OCI extensions based on

CDA response should be correlated with

laboratory analysis for each engine, lubricating oil and fuel type. The probability of oil decreasing TBN increases

between 800-2000 hr and at a CDA

reading of 3.0-6.0 for the engines tested

in this study.

2. Oil samples from stationary diesel engines that used bypass filters showed

no less oil contamination than control

samples. Other studies have revealed

that oil change intervals can be extended when using bypass filters, but

they had no control data. The Power

Plus used-oil blend unit limits oil degradation and eliminates waste oil for stationary diesel engines. The Power Plus

unit is efficient, effective and affordable. Based on a 5,000 hr/yr operational period, engines at one site

(Unalaska) saved over 2,000 gal/yr. One

engine at Unalaska, and the engine at

Seward, eliminated waste oil while using the Power Plus re-blend technology. Based on a 5,000 hr/yr operational period, engines at one site

(Unalaska) saved over 2,000 gal/yr of

lubricating oil.

3. Small isolated communities can reduce

the amount of waste oil they generate.

However, the ability to do so is based

primarily on operator interest and desire to closely monitor the engine. This

increased attention is needed because

degradation levels need to be determined individually for each engine and

oil by establishing baseline data. 

The study further found no significant

health hazard from PAHs in the used oil

sampled resulting from oil exchange intervals or burning used oil.

The full report was submitted in partial

fulfillment of Contract Number

CR-817011-01-0 by the Alaska Health

Project under the sponsorship of the U.S.

Environmental Protection Agency.
6

Todd Sigaty, Carl Reller, and Daniel Middaugh are with Alaska Health Project,

Anchorage, AK 99501.

Paul Randall is the EPA Project Officer (see below).

The complete report, entitled "Waste Oil Reduction for Diesel Engines," (Order No.

PB96-196779; Cost: $28.00, subject to change) will be available only from:

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

Telephone: 703-487-4650

The EPA Project Officer can be contacted at:

National Risk Management Research Laboratory

U.S. Environmental Protection Agency

Cincinnati, OH 45268

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

Official Business

Penalty for Private Use $300

EPA/600/SR-96/092

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT NO. G-35