Understanding Oil Contaminants
By Tom Bock
In the past few months we have seen an increase in the number of oil samples with increased soot levels. This increase is most likely from excessive idling to maintain air conditioning levels, the increase in dust in the air that is trapped in air filters due to drought in the Midwest or the increase in “BUGS” in the fuel that grow faster in hot temperatures.
Due to the nature of diesel engines .whereby the fuel and air mixture combusts spontaneously from the high pressure of the cylinder instead of igniting from a spark plug like gasoline engines. This process produces soot incomplete fuel combustion that usually caused by incorrect fuel to air ratios, improper mixing of fuel and air that causes uneven burn, or blow-by that decreases the pressure required for complete combustion.
The soot is usually smaller than 1 micron and the dispersant additives formulated in motor oil to keep the soot from clumping together and causing damage protect the engine from damage. However as the levels increase the additive are overwhelmed and clumps form impeding the flow of oil, increasing viscosity, attaching to parts and causing wear and retaining heat that does not allow the oil to cool.
There are some simple steps that can be taking to lower the soot production of diesel engines.
- Keep air filters clean. Blocked air flow will affect the fuel/air ratio
- Check air induction system for leaks loose clamps, holes in ductwork etc.
- Keep injectors clean and operating correctly. Injectors that do not spray the fuel in cylinder properly do not allow the fuel to mix with air effectively
- Ensure injector timing is correct, if injected too late in cycle fuel will not burn properly
- Check fuel tank for “BUGS” black bacteria that contaminates fuel reducing the fuels ability to burn clean by clogging fuel filter reducing flow. Check the fuel filter frequently in hotter months if black dots appear install biocide in tank.
- Watch fuel mileage if there is a drastic drop chances are it is due to unburned fuel that may be due to above or loss of compression in cylinders due to blow-by, valve seating etc.
- Improper or clogged muffler could also cause back pressure that could affect air flow. The DPF may require regeneration etc.
There may be other causes for soot increase but if you know that it is occurring based on your oil sample results you can react and take corrective measures. It’s your $$$$$ why waste it running with an engine that does not burn the fuel you pay for.
A comprehensive oil sample is usually $20 or less, the value of the information you receive will far exceed the cost. Sample your oil regularly whether you use an extended oil drain filtration system or dump your oil at set intervals.
If you have any questions pertaining to oil or oil sampling please send them to firstname.lastname@example.org with the subject line : MOVIN’ OUT question.