compare with oil in the equipment or determine if unusual metal content in the sample is the
result of lubricant chemical composition.
On-Condition Oil Change. An AOAP process where the oil in enrolled components will not be
changed in accordance with the equipment Lubrication Order. While oil samples from the
enrolled component are being tested in the laboratory for internal part wear, the laboratory will
also test the oil sample to determine if it has been contaminated. Component system lubricants
will be changed when the AOAP laboratory notifies the unit the oil is no longer serviceable.
Equipment under warranty will still comply with all requirements of the warranty.
Resample. An additional or follow-up oil sample requested by the laboratory to confirm test
findings indicating potentially serious conditions, when the oil sample appears to have been
contaminated or there is insufficient lubricant to conduct the required testing.
Special Samples. AOAP samples submitted to the laboratory for analysis, other than routine or
laboratory requested samples.
Spectrometric Analysis. A test used to detect concentrations of various wear metals, which are
smaller than the human eye can see in oil samples. The friction of moving parts initiates wear in
mechanical systems, producing metal particles of microscopic size. These metal particles enter
the oil stream and are uniformly dispersed and suspended throughout the lubricating oil system.
Spectroscopy detects the kinds and quantities of the different metallic particles in the sample.
Analyses identify the wear-metal elements aiding in the determination of the rate of part wear
and source of wear. Through scheduled sampling and testing of the oil from the mechanical
system, abnormal wear levels can be easily detected. The worn parts can be repaired or replaced
before they cause damage to the entire assembly or mechanical system.
Viscosity. Viscosity is the `rate of flow' of lubricating fluid that can be affected by high
temperatures, contamination, and aeration during service, which promotes oxidation. Oxidation,
if allowed to continue, leads to increased viscosity and the formation of varnish and sludge.
Viscosity decreases are usually attributed to fuel dilution or contamination by coolant. The
viscosity of used lubricating fluids is determined by a viscometer. These readings may be
compared to new oil viscosity specifications and provide an indication of used oil condition.
When the lubricant viscosity in equipment no longer meets factory specifications, it may no
longer be able to lubricate, cool, and protect the internal parts of a component.
components, suspended in used oil or grease.
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