90,000 MILE DIESEL
ENGINE OIL CHANGES?
- GOALS:
- 1. To understand the use of synthetic oils in diesel engines.
- 2. To understand how longer crankcase drain intervals can save energy.
- OBJECTIVES:
- The student will:
- 1. be aware of the differences between natural and synthetic diesel engine oils.
- 2. recognize that synthetic diesel-engine oils extend crankcase oil drain intervals and the use of these oils can save energy by reducing internal engine friction.
- 3. learn that synthetic diesel engine oils reduce the demand on oil stocks.
- 4. understand that synthetic diesel engine oils reduce disposal, recycling costs, and potential environmental pollution.
- LESSON / INFORMATION:
- Sixty-thousand (60,000) mile diesel oil change intervals have been successfully achieved in fleet operation using Amsoil synthetic based oils. Amsoil has produced premium, synthetic based API approved diesel engine oils since 1972. Present fleet tests of 90,000 mile drain intervals have found the oil free and clean of deposits and suitable for continued use. Amsoil claims a four to eight percent increase in fuel economy when using their product.
- Mack Truck has recently approved 25,000 mile crankcase drain intervals, up from 15,000 and 20,000 mile intervals formerly recommended. These increased intervals are effective for most 1990 and later model vehicles used under on-highway conditions. These are a part of the "new breed," lower emission engines currently in production. Other manufacturers, Detroit Diesel, Cummins, and Caterpillar, have also increased their recommended drain intervals. These changes are based on using new API CF4 rated oil. Oil that meets this standard is necessary for these new engines to meet desired operational, emission, and longevity standards. Many diesel engine oil experts forecast that in the near future diesel oils (CG) will be classed as diesel only. Many current multi-viscosity oils are classified SE/SF/CF. This "wide spectrum" oil may be used in gasoline or diesel engines. Diesel only oils will carry no "S" classification. Oil consumption and crankcase contamination are reduced by using a newly designed upper piston and piston ring. Reduced blow-by gases reduce crankcase contamination. Higher reach upper rings and oils containing greater dispersants reduce oil consumption. At approximately $6.00 per gallon for the new type oils vs $5.00 per gallon for older type oils, increased operational costs could be forecasted. However, in 75,000 miles, only three oil changes would be necessary for the newer type oil vs. five changes for the older type oil. With a typical over-the-road diesel truck using fourteen gallons of oil per change, a significant savings of $98.00 may be realized.
- 14 gallons X $6.00/gallon X 3 changes in 75,000 miles = $252.00
- 14 gallons X $5.00/gallon X 5 changes in 75,000 miles = $350.00
- $350.00 - 252.00 = $98.00
- This is for oil cost only! Labor and disposal costs could easily equal the cost of the oil itself. Used engine oil disposal costs accumulate rapidly. These costs include storage, contract pick-up costs, hazardous material disposal cost, and sludge disposal cost. At one time used oil was collected at no cost. At times a small fee was paid for used oil since oil change stations "dumped" used oil. Environmental issues prohibit used oil dumping, thus, collection, transportation, and disposal costs could equal the cost of new, clean oil. Some used oil collectors sell to re-refiners to produce asphalt or other low grade petroleum products.
- Synthetic oils are made by rearranging carbon and hydrogen atoms into new molecules. These molecules are more stable, resist oxidation at higher temperatures, and are less volatile than paraffin based oils. Because they are more stable, they resist reaction by combustion gases and become less contaminated over time. Oil itself does not "wear out" but becomes chemically contaminated. Over time, additives become depleted and acid levels rise. Oxidation and volatile boil-off are the primary reasons for changing oil. Oil properly filtered, chemically stable, and with the proper additives is serviceable.
- A key factor to long interval oil changes is oil analysis. Many companies, such as Quaker State, have suggested oil analysis for many years. By analysis, the condition of the oil may be determined. With oil analysis, recommended additive levels can be maintained; the analyzing lab may recommend changing only the filter, adding certain additives, and "topping off" the crankcase. At other times, they may recommend draining and replacing the oil. For new vehicles under warranty, it is important to consult with manufacturer's representatives to assess the effect that extended drain and oil analysis have on engine warranties.
- Filter design, quality and change interval are vital to any engine, but especially to one using extended drain intervals. Filters trap fine metal particles, combustion soot, water sludge, and other by-product contaminants. The trapping process reduces engine wear and keeps the oil clean and serviceable.
- ACTIVITY:
- Using the attached data sheet, compare four different diesel powered trucks for recommended oil change, filter change, type of oil and cost of operation for 300,000 miles.
- 1. Obtain the manufacturer's recommended oil and filter change intervals and capacity for two diesel powered trucks built before 1990.
- 2. For the same brand and engine class as in number 1, obtain the manufacturer's recommended oil and filter change intervals and capacity of two diesel powered trucks built in 1992 or later.
- 3. Determine the cost of each recommended type of oil.
- 4. Determine the cost of each recommended type of filter.
- 5. Determine the labor cost for each oil change.
- 6. From a local outlet that changes engine oil in significant quantities, determine their waste oil disposal costs per gallon.
- 7. Calculate the net cost of using synthetic, long drain vs. standard drain oils for 300,000 miles.
- 8. Summarize this activity.
- ACTIVITY SHEET
- A. #1 1990 or older:
- Year__________
- Make________________________
- Engine Type________________________
- Crankcase capacity________________________
- Recommended oil_________________________
- Recommended filter__________________________
- Recommended filter change_________________________
- #2 1990 or older:
- Year__________
- Make________________________
- Engine Type________________________
- Crankcase capacity________________________
- Recommended oil_________________________
- Recommended filter__________________________
- Recommended filter change_________________________
- #1 1992 or newer:
- Year__________
- Make________________________
- Engine Type________________________
- Crankcase capacity________________________
- Recommended oil_________________________
- Recommended filter__________________________
- Recommended filter change_________________________
- #2 1992 or newer:
- Year__________
- Make________________________
- Engine Type________________________
- Crankcase capacity________________________
- Recommended oil_________________________
- Recommended filter__________________________
- Recommended filter change_________________________
- B. Determine costs of:
- Natural oil $________.___/gallon --- filter $________.___
- Synthetic oil $________.___/gallon --- filter $________.___
- Labor for oil change $________.___ ---- filter $________.___
- Disposal of used oil $________.___/gallon --- filter $________.___
- Oil analysis $________.___
- C. Calculate oil change cost for 300,000 miles for each truck (Example - 14 gallons needed per change, 1 filter every 7500 miles, 1 oil change every 15,000 miles)
- Recommended oil cost $5.00 per gallon.
- Recommended filter cost $46.00
- Labor is $75.00 per change.
- Disposal cost is $1.50 per gallon.
- 300,000/15,000 = 20 oil changes
- 300,000/7,500 = 40 filter changes
- 20 changes X 14 gal/change = 280 gallons
- 280 gallons X $5.00/gal = $1,400.00
- 280 gallons X $1.50/gal disposal = $420.00
- 40 filters X $46.00/filter = $1,840.00
- 20 changes X $75.00/labor charge = $1,500.00
- Net cost for 300,000: $1,400.00 + 420.00 + 1,840.00 + 1,500 = $5,160.00
- 300,000 mile oil cost:
- Truck #1 $__________
- Truck #2 $__________
- Truck #3 $__________
- Truck #4 $__________
- D. Summarize the oil cost for operating a diesel truck.
- INFORMATION CHECK
- Directions:
- Indicate whether the statements below are true or false. If the statement if false, explain why it is false.
- 1._______ All engine oils are paraffin based.
- 2._______ API SC engine oils are suitable for most heavy duty diesel powered engines.
- 3._______ Chemical change and loss of oil additives are the chief reasons for changing engine oil.
- 4._______ Used oil disposal costs are minimal.
- 5._______ Oil filters extend the useful life of engine oil.
- 6._______ Oil analysis is an important part of long distance oil changes.
- TEACHER'S NOTES:
- Students need to become aware what it really costs to change oil. In the past, mechanics and automotive engineers have recommended frequent oil changes to protect engines and extend product life. We have always said "oil is cheap; engines are expensive." Since there were so many variables in vehicle operation, our recommendations have always been rather conservative. Today, with oil analysis and synthetic oils, oil drain intervals could be extended significantly. The environmental and energy issues demand that present and future technicians be aware of the latest recommendations for oil and filter service.
- ANSWERS TO INFORMATION CHECK:
- 1. False. Synthetic oils are not paraffin based.
- 2. False. Diesel engines require a "C" rated oil such as CB, CC, CE, etc.
- 3. True.
- 4. False. These costs can be substantial. They can equal the cost of new oil.
- 5. True. This is their primary purpose.
- 6. True. Even the best oils lose their additives and become chemically contaminated.
- RECOMMENDED READING:
- Diesel Engine and Fuel System, 2nd Edition. Pages 168-169
- REFERENCES:
- Dagal, John F. Diesel Engine and Fuel System Repair, 2nd Edition. John Wiley & Sons, Inc. New York, NY. 1988.
- New PM Programs, Part 2., Fleet Equipment Pages 16-21. May 1992
- Do New Engines Mean New PM Programs? Fleet Equipment Pages 24-28. March 1992.
- Cummins Bulletin 3385896. Cummins Engine Co., Inc. Columbus, IN. 1992.
- OIL and the Engine Make. Fleet Equipment Pages 22-25. January 1993.
Comments or questions to: TechAsmt@LA.GOV
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