Lube Oil Cleanliness tests check fluid cleanliness in terms of water and particulate contamination. While they are typically performed on in-service oil as part of predictive / proactive maintenance, they may also be used as a quality control tool for new lubricant oils.
Lubricant Oil Cleanliness
Recommended Tests:
Particle Counting Test, Laser-Blocking
Water by Coulometric Karl-Fischer (ASTM D6304-00)
1.    Particle Counting (ISO)
The Particle Counting test is used to identify and measure oil cleanliness by determining the particulate contamination of the lubricant sample. In circulating lubrication systems, oil is used for the purposes of lubrication, power transmission, surface protection, heat transfer and surface cleansing. Particulate contamination in the lubricant can cause equipment failure through abrasion of moving parts, adhesion to the surfaces of moving parts and corrosion.
Particle Counting test results in ISO 4406 Codes are reported for particle sizes > 4/6/15 μm in the Metalux Lubricant Condition Report. 
2.    Coulometric Karl Fischer (KF)
METALUX performs the Karl Fischer test by titration to determine the amount of water in the oil sample. Results are reported in ppm (parts per million) according to ASTM D6304-00.
The presence of abnormal water level within any lubricated system decreases the lubricant’s ability to effectively lubricate the metal surfaces and causes rust (red oxides) and corrosion. Due to the accelerated lubricant contamination water causes, water contamination is a common cause of equipment failure.