Understanding Oil Contaminants
By Tom Bock
When wear metals show up in oil samples most people will point to the filtration system thinking that the filter failed to capture all the particles. What they really should be asking is; where did the metal come from? And why is the engine shedding the metals?
The answer may not be so obvious. Sure the wear could be caused by oil that has lost the properties that are required to properly, cool and disperse the contaminants. But the real culprit is the liquid contaminants Glycol, Fuel and Water coupled with Soot development that breaks the oil down and renders the protective additive package ineffective.
Glycol enters the oil through defective seals, cracked head or cylinders, blown head gaskets or deterioration of copper tubing in oil coolers etc. Glycol causes increased soot coagulation, sludge, oil balls that clog filters, increased viscosity levels and oxidation that forms acids. Owners who do not sample the oil frequently will never know they have a glycol intrusion that will eventually cause engines parts to fail.
Fuel Dilution is usually caused by injector leakage, poor fuel combustion, and defective fuel pump seals. The fuel will decrease the viscosity of the oil that causes premature wear, dilute the oil additives, and increase acid levels reducing the effective base additives in the oil. Lower viscosity will accelerate the engine wear and will cause parts to fail.
Water enters the oil through condensation and is one of the most destructive contaminants as the water mixes with oil reducing viscosity, it saturates the soot causing sludge and carbon deposits that attach to moving parts scoring and increasing engine wear. The water provides the H20 that is required to form the sulfuric and nitric acid when mixed with soot and fuel residue.
Soot is created naturally when fuel is burned and is combustion by product. The key is to keep the soot generation to a minimum. Keeping the engine working properly with correct fuel to air ratio, proper fuel injection and keeping the blow-by under control will reduce the soot generation. Keeping the liquid contaminants out of the oil will allow the soot to remain in suspension and not harm the engine. Once the soot mixes with water, fuel or glycol sludge develops clogging filters, decreasing flow and ultimately causing damage.
The key is to sample oil frequently and make necessary minor repairs before they become major expenses. Use a quality filter and motor oil to keep soot to a minimum and remove the liquid contaminants before they can react with the soot.
There are many products on the market that will help control the liquid contaminants and I highly recommend you research each product to find out which one will work best for your engine.