What Is Sludge and Is It in My Engine?
Most people think their engine doesn’t have sludge, especially if they regularly change their oil. They don’t realize sludge is a normal product of oil and moving machine or metal parts. With gas or diesel motors, the problem is worse for carbon produced from combustion that combines with oil to make varnish-like, liquid grit, and drastically increases (magnifies) wear and tear through continual depositing.
Although one would think the oil appears to be at fault, that’s wrong. The oil is actually the victim of mechanical and chemical attack. The formation of sludge is a complex interaction of components. These components are soot, engine heat, fuel, water, acids, and dirt.
Let’s start with:
Soot – This is fine powder that is a product of incomplete combustion. This carbon substance enters the crankcase with exhaust blow-by gases that escape past the piston rings. Since soot is a very fine powder, it thickens oil by a process called “soot loading.” It gels the oil like a cake mix thickens milk.
Engine Heat – A natural result of internal combustion, engine heat takes its toll on your motor oil. In the presence of air, oil undergoes a process called oxidation, which becomes more severe as the temperature increases. Oxidation thickens the oil and produces corrosive acids. Left unchecked, your oil would degrade into a tar-like mess.
Fuel – The fuel enters your crankcase with exhaust blow-by gases in unburned and partially burned forms. It is chemically unstable; therefore, it reacts with itself and the oil to form gums and varnishes that create even more oil thickening.
Water – Water gets into your crankcase typically through condensation or in exhaust gases that escape past the piston rings. The engine’s job is to get rid of this moisture by operating at sufficiently high temperatures. However, all engines operate periodically at low temperatures and experience some water contamination. When this occurs, water becomes emulsified, meaning it is absorbed by the oil and thickens the lubricant. As a result, the oil does not flow or cool well. The increased viscosity can cause the oil to burn, creating engine deposits.
Acids – When fuel burns, some products of combustion react with moisture in the system to form acids. These include sulfuric, hydrochloric, and organic acids. Sulfur-based acids are undesirable because they attack the oil, reducing its detergent efficiency. Organic acids react with unburned fuel to promote sludge and varnish. In addition, acids can cause additive settling, or dropout.
Dirt – Most people associate dirt with engine wear, but dirt can also play a role in sludge formation. Wear of piston rings and cylinder walls causes an increase in piston blow-by. Since the exhaust gases contain many harmful byproducts, their presence in the crankcase should be minimized. Nonetheless, some of these compounds will escape past the rings. Auto-Rx® Plus will fight the harmful effects of dirt. The dispersant suspends and isolates the dirt, soot, and other solid particles that work their way into the oil. That is why an oil change is necessary to flush the unwanted components.
Heat, when combined with engine oil, also creates harmful byproducts such as sludge, varnish, and sulfur. When these byproducts combine with condensation and airborne pollutants (dirt, soot, industrial ash, etc.), contamination build-up is created. Contamination buildup enters the oil passages in the engine, limiting the amount of oil that can get to the most vital parts of the engine. This buildup prevents engine oil from properly lubricating the engine. When proper lubrication fails to occur, uneven hot spots are created underneath contamination deposits, resulting in a dramatic decrease in engine performance and shortening the life of the engine.
Unfortunately, there is not much that engine oil can do to reduce the harmful effects of all these contaminants. Oil changes every 3000 miles and the Auto-Rx® Maintenance Plan are the best way to take care of this problem.