Filters have been standard equipment on engines since 1935, to remove abrasive particles from air and oil before circulation through the engine, thus protecting it. However, filtration has developed since then and today, lubrication products with specialist additives enable the use of more compact full flow filters. This is because detergency and dispersancy (the property that allows the oil to suspend and carry away pollutants from various sources) has reduced the element plugging and the total “dirt” holding requirements.
Callum Ford, National Marketing Manager at Lubrication Engineers (LE) South Africa, says that although the technology has been improved over the years, the goal of the filter system remains the same: to protect the engine against wear from solid particles, moisture, oxidized matter and corrosive products.
Contaminants generally found in lubrication oils, which filters are expected to remove, comprise a few common categories. These include:
- Airborne solids
- Soot from combustion
- Corrosive material (acids)
- Wear solids
- Oxidized material from lube oil and fuel
“The amount and particle size of these contaminants will vary with the engine type, oil type and engine operating conditions, but the ways that a filter will get plugged remain the same, says Ford. “There are six ways this can happen.”
- Impaired dispersancy comes about as a result of moisture and coolant leakage, causing insolubles to “dump out” of the oil. It can also be caused by a combination of moderate soot load, low pH and a high level of oxidation products.
- Excessive contamination is where the oil becomes saturated with combustion contaminants, such as soot.
- Absorption or filtration of oxidation products happens because of fuel dilution and overheating.
- Additive precipitation is a result of excessive moisture in the crankcase.
- Gel formation is the result of coolant and/or moisture combining with the oil additives to form a gel.
- Wear debris and abrasives is due simply to an excessive accumulation of these solids in the oil.
“A higher quality of engine oil helps prevent the occurrence of these filter plugging mechanisms,” says Ford. “Studies have shown that high oil filtration efficiency not only reduces engine component wear, but increasing the oil quality also results in reduced oil ring wear and piston deposits. The lubrication specialists at LE South Africa are able to recommend the best product for your specific application and requirements by doing a technical assessment and an oil analysis. We also recommend using lower porosity filter elements, as these have been shown to reduce engine wear.”
He says that lubrication theory can get quite complex – understanding detergent versus non-detergent oils, the use of smaller micron filter porosities, the types of additives available and the role they play, etc. However, a reliable lubrication partner with appropriate tribology training and field experience will be able to assist in ensuring your engine is protected at all times.