Oil Analysis - Physical Analysis
This involves a visual assessment of lube oils to identify gross contamination. Large metal and dirt particles and foreign bodies that are too big to be analysed by ICP-OES would go unnoticed without this simple check.
To simplify matters we have developed an arbitrary numerical scale that differentiates between types of visual contamination in oils. The scale appears on the back of every hard copy report we produce and can also be viewed below:
| Appearance Rating | Description of the Lubricant |
| 10 | Clear and Bright |
| 20 | Dark |
| 30 | Hazy |
| 40 | Cloudy |
| 50 | Emulsified (Milky) |
| 60 | Free Water |
| 70 | Solid Debris |
| 80 | Solid Debris and Free Water |
Viscosity
The resistance to flow is measured by the time taken for a given volume of oil to flow under gravity between 2 points in a calibrated viscometer tube.
Viscosity measurements are essential to establish the correct grade of the oil in use, eg SAE 30 or 15w40. Slight changes in viscosity are to be expected during use, but abnormal changes must be detected and reported.
Abnormalities are indicative of one or more of the following problems:
Overheating
Fuel Dilution
High Insolubles
Excessive use
General contaminants
Wrong Oil Grade
All lubricating oils have a standard unused oil viscosity which is used to determine tolerances in the analysis of the in-service oil:
A 15% change from the unused is considered to be cautionary and a 20% change considered abnormal. For example an oil of ISO 100 grade will be subject to the following limits:
Normal - between 85Cst and 115Cst (Centistokes, the units of kinematic viscosity)
Caution - between 80Cst and 85Cst or between 115Cst and 120Cst
Serious - less than 80Cst or more than 120Cst
Click the links to browse & find out more
Got a question ? mail@oilanalysis.org.uk
Fully UKAS accredited, quality assured
Professional service with full support
UK's largest independant oil laboratory