Oxygen exposure, heat and contaminants cause all oils to degrade. Engine oil is particularly susceptible to degradation by sulfur, nitration, by-products of combustion, high temperatures, and water from the combustion process or condensation. Oil Condition Analysis, part of a comprehensive oil analysis program, helps prevent component damage by monitoring your oil and keeping track of its degradation. Oil Condition Analysis also allows you to correct problems that affect oil performance. The bottom-line benefit: maximum oil performance, optimum oil change intervals and reduced repair costs. Oil Condition Analysis is performed on most oils from transmission, engine, and hydraulic systems.
Understanding Oil Condition Analysis
Oil Condition Analysis is similar to Wear Rate Analysis with one important exception: It evaluates chemical compounds in the oil rather than wear element particles.
Oil Condition Analysis is important for oil from all systems: transmissions and hydraulics, as well as engines.
It works like this:
- You submit a sample of new oil from your source of supply (unused), called “reference oil,” when you initially enroll in the Macallister Machinery fluid analysis program and whenever you get new shipments of bulk oil. Reference oil samples are processed at no cost to you. If you are using Cat oil, reference oil samples may not be necessary. Advise your Macallister Machinery lab of the brand and viscosity rating of all oils used in various systems by submitting a reference sample for each different oil type. Each oil type should have its own oil reference sample registered with our lab. Inexpensive sampling kits can be purchased at your local MacAllister Machinery location for this purpose. Cost for this kit is minimal since the analysis of reference (unused supply) oils is free. You can then indicate that the sample is a “reference” by checking the reference sample box to the right of the appropriate compartment identification on the sample label. Indicate the oil brand and viscosity rating in the appropriate section of the label.
- The new oil is scanned by a special instrument using infrared light. Information is stored in the instrument’s memory.
- At each scheduled interval, you submit a sample of used oil and indicate the brand and viscosity rating on the information label.
- The Oil Condition Analysis instrument focuses a beam of light through a film of used oil and records the data.
- The instrument uses a mathematical formula to compare the used and new oils and quantify any differences.
Identifying Contaminants Before They Cause Problems
Oil Condition Analysis detects soot, oxidation, nitration products and sulfur products/acids. This test can also detect contamination by water, fuel and glycol from coolant. If detected, specific contaminant tests are used to confirm findings.
Oil Condition Analysis focuses on:
Soot is found only in engine oil. It is the insoluble residue of partially burned fuel. It is held in suspension by the oil additive package and causes engine oil to turn black. When soot drops out of suspension in the oil, it contributes to additive depletion and eventually increases oil viscosity. Heavy concentrations of soot can cause bearing damage by starving contact surfaces of lubrication.
Oxidation occurs in transmission, hydraulic and engine oils when oxygen molecules chemically join with oil molecules. This chemical reaction is accelerated by high oil temperatures, glycol contamination from engine coolant, the presence of copper, and from extended oil change intervals. Oxidation causes the oil to thicken, form acids, and lose lubrication qualities, which threatens the life of your components. Oxidized oil will cause deposits on engine pistons and valves, stuck rings, and bore polishing. In hydraulic systems and transmissions, it can cause valve scuffing and sticking.
Nitration occurs in all engine oils, but is generally only a problem in natural gas engines. Nitrogen compounds from the combustion process thicken the oil and reduce its lubricating ability. If nitration continues unchecked, it can result in filter plugging, heavy piston deposits, lacquering of valves and pistons, and eventual failure.
Sulfur is present in all fuels and affects all engines. During combustion, fuel sulfur oxidizes, and then combines with water to form acid. Acid corrodes all engine parts, but is most dangerous to valves and valve guides, piston rings and liners.
Glycol, Water and Fuel Detection
When present in your engine oil or fluid power system, water, glycol (coolant) or fuel can indicate a number of problems, from incorrect engine timing (fuel) to cooling system leaks. By detecting these problems before they cause component failure, we can work with you to schedule downtime and maximize productivity.
Glycol causes rapid oxidation of the oil and usually indicates a cooling system leak. Severely oxidized oil becomes sticky and forms sludge that plugs me filter. Any amount of glycol contamination in the oil is unacceptable. Engines, hydraulics or transmissions using water-to-oil coolers may become contaminated with coolant if a leak develops in a cooler tube or seal.
If infrared analysis indicates the presence of water, the approximate amount is determined by placing a drop of oil on a plate heated to between 2300 and 2500 F. If water is present the oil will bubble and sputter. By comparing the amount of bubbling to laboratory control samples, experienced laboratory technicians can determine the quantity of water in the sample. Any amount over 0.5 percent is considered excessive.
Water can contaminate a system by leaking in from the outside or condensing in the engine’s crankcase or compartment. When water combines with oil, it reduces the oil’s ability to lubricate and forms a sludge that plugs filters. Water passing between very close components can create “hot spots.” If the water gets hot enough, it causes tiny steam explosions that can fracture metal.
Fuel contamination is confirmed using a flash test in which the used oil is heated to a prescribed temperature in a closed cup, and then subjected to a flame. Fuel vapors driven off by the heat will flash if the dilution exceeds four percent.
Fuel in the engine oil reduces its lubricating properties. Small amounts of fuel are common as a result of the combustion process. But if fuel levels exceed recommended levels, we will suggest a check for defective fuel injection nozzles and other sources of leakage. Fuel dilution is generally the result of extended idling, incorrect timing, or a problem with the fuel injectors, pumps or lines.