From Trains Magazine, February 2003 issue, in the Ask Trains section: (Bold type is my comments)
It's time to get the oil changed in my car again, so I wonder, how often do railroads change oil in locomotives? What is the interval before service is required, and how is it measured, in miles, hours or days? - Neil Seely, Rochester, N.Y
Lubricating oil almost never wears out, but it does beome contaminated and its chemical aditives depleted. Cars use such a small amount of oil it makes more economic sense to change it. Locomotives use large quantities of lube oil, so it is replenished. Locomotive oil filters are changed regularly, usually the same time the locomotive undergoes a Federal Railirad Administration mandated periodic inspection.
Oil filters for an SD40-2, the most common locomotive ever built, has a V-16 diesel, 645 ci displacement per cylinder, or roughly 169 Liters for the entire engine) for example, are typically changed during the FRA 92-day inspection. Newer engines have better filter media, bigger filters, and oil has been improved too, all in pusuit of less downtime for maintinence. The SD70M has doubled the filter change interval to 180 days.
Oil is contaminated by three things: fuel, from leaking in or fuel lines; water, primarily from coolant leaks; and solid particles, mostly soot from incomplete combustion blowing by the piston rings.
Railroads regulary analyze lube oil with a spectrograph in a laboratory. The presence or absence of substances in the oil shoes many things, such as fuel contamination or incipient main bearing failure. On this basis, the oil might be changed, but more typically the cause of the contamination is diagnosed and resolved.
As mentioned above, diesel locomotives consume large quantities of lube oil - 25 to 30 gallons per week in heavy service, practically all of it left in a thin film on the upper cylinder walls as the piston scrapes downwards, then consumed in combustion. So the oil is in effect changing itself constantly. The fuel contamination evaporates off or is combusted, the water evaporates, and the solid particles are removed by the filters. Every engine will have some raw fuel in its oil from blow-by, but unless there are a lot of solid contaminants for it to adhere to it will be evaporated.
Adding oil is a maintinence item, so in the 1970's most railroads started specifying increased lube oil capacities. The lube oil capacity of a "basic oil pan" SD40-2 is 243 gallons, whereas an "increased capacity oil pan" is 395 gallons. That extends the oil replenishment interval from once every 15 days to once every 60 days for an SD40-2.
Oil is reglarly "sweetened" with chemical additives, based on laboritory analysis:
-detergents to consolidate solids so they are large enough to be caught by the filters
-anti-corrosives because fuel contains trace amounts of sulphur which becomes sulphuric acid during combustion
-Ph-mediators to maintain the acid-base balance of the oil and limit galvanic corrosion of the many metals that make up a diesel engine.
There is a little more to the story, but it mostly junk a locomotive fan would care about. The quantities of lubes we use seem to pale in comparison to these beasts!
It's time to get the oil changed in my car again, so I wonder, how often do railroads change oil in locomotives? What is the interval before service is required, and how is it measured, in miles, hours or days? - Neil Seely, Rochester, N.Y
Lubricating oil almost never wears out, but it does beome contaminated and its chemical aditives depleted. Cars use such a small amount of oil it makes more economic sense to change it. Locomotives use large quantities of lube oil, so it is replenished. Locomotive oil filters are changed regularly, usually the same time the locomotive undergoes a Federal Railirad Administration mandated periodic inspection.
Oil filters for an SD40-2, the most common locomotive ever built, has a V-16 diesel, 645 ci displacement per cylinder, or roughly 169 Liters for the entire engine) for example, are typically changed during the FRA 92-day inspection. Newer engines have better filter media, bigger filters, and oil has been improved too, all in pusuit of less downtime for maintinence. The SD70M has doubled the filter change interval to 180 days.
Oil is contaminated by three things: fuel, from leaking in or fuel lines; water, primarily from coolant leaks; and solid particles, mostly soot from incomplete combustion blowing by the piston rings.
Railroads regulary analyze lube oil with a spectrograph in a laboratory. The presence or absence of substances in the oil shoes many things, such as fuel contamination or incipient main bearing failure. On this basis, the oil might be changed, but more typically the cause of the contamination is diagnosed and resolved.
As mentioned above, diesel locomotives consume large quantities of lube oil - 25 to 30 gallons per week in heavy service, practically all of it left in a thin film on the upper cylinder walls as the piston scrapes downwards, then consumed in combustion. So the oil is in effect changing itself constantly. The fuel contamination evaporates off or is combusted, the water evaporates, and the solid particles are removed by the filters. Every engine will have some raw fuel in its oil from blow-by, but unless there are a lot of solid contaminants for it to adhere to it will be evaporated.
Adding oil is a maintinence item, so in the 1970's most railroads started specifying increased lube oil capacities. The lube oil capacity of a "basic oil pan" SD40-2 is 243 gallons, whereas an "increased capacity oil pan" is 395 gallons. That extends the oil replenishment interval from once every 15 days to once every 60 days for an SD40-2.
Oil is reglarly "sweetened" with chemical additives, based on laboritory analysis:
-detergents to consolidate solids so they are large enough to be caught by the filters
-anti-corrosives because fuel contains trace amounts of sulphur which becomes sulphuric acid during combustion
-Ph-mediators to maintain the acid-base balance of the oil and limit galvanic corrosion of the many metals that make up a diesel engine.
There is a little more to the story, but it mostly junk a locomotive fan would care about. The quantities of lubes we use seem to pale in comparison to these beasts!
