Viscosity Test & Viscosity Testing

The analysis of used oil samples from engines provides detailed information regarding the internal condition of the engine and its components.

What is Viscosity Testing?

A lubricant's viscosity is of critical importance in ensuring that the lubricant can provide the correct film thickness in a given machine or application to ensure that metal components do not rub against each other and create component wear.

Viscosity Test & Viscosity Testing

Monition Ltd operate one of the UK's largest independent Oil Analysis Laboratories, and provide Viscosity Testing on used-oil samples, as well as offering a suite of complementary and specialist analysis services for the precise interpretation of oil and machine condition.

What does a Viscosity Test tell us?

Viscosity is one for the key Laboratory tests conducted on used-oil samples in order to determine condition. A Viscosity Test of an oil sample provides an indication as to the correct grade of oil in use, Oxidation/Overheating, Fuel dilution and oil mixes.

A drop in Viscosity can indicate:

Fuel dilution, oil mix (mixed grades or fluid leaks from adjoined components).

An increase in Viscosity can indicate:

Oil mix, Coolant leak, water ingress, emulsified oil, oil degradation & breakdown.

Industrial Applications for Viscosity Test

Understanding the condition of lubricants in industrial machines and systems such as gearboxes, pumps, motors, engines etc, is a key consideration within the field of Predictive and Condition-Based Maintenance.

If a lubricant's target Viscosity level changes abnormally as a result of use, then the lubricant's ability to provide protection to a machine's components will become compromised, and the machine will be at risk of breakdown in service.

Oil analysis offers a detailed understanding of a machine's internal condition without the need to pull the machine from service to undergo a strip-down. Regular oil analysis should be conducted by Maintenance Engineering teams on a periodic basis in order to ensure plant and production reliability can be maintained, and mechanical breakdowns in service can be averted.

Viscosity Test Services

Monition as a specialist Condition Monitoring service provider, Monition can advise and assist customers to establish a program of oil analysis condition monitoring, and provide engineering services if required to conduct the sampling onsite.

Monition Ltd's Oil Laboratory provides a specialist suite of lubricant analysis, including Kinematic Viscosity Testing, in order to advise customer's of the condition of lubricants and their machines.

Monition's ISO 9001:2000 accredited service includes:

  • Supply of Oil sampling kits
  • FREEPOST return envelopes (UK only)
  • Screening of Samples on arrival at Lab
  • Detailed Oil Analysis
  • Clear, fully interpreted Reports including recommendations for corrective actions, emailed directly to customers Online Reporting facilities available

Viscosity Test

There are many methods of determining the Viscosity of Oils/ fluids. The two standard methods are Dynamic Viscosity and Kinematic Viscosity.

Dynamic viscosity utilises the technique of measuring the resistance to movement. For example, in a Dynamic Viscometer, oil and a ball bearing is added to the instrument. Utilising the magnetic properties of the ball bearing the Viscometer measures the speed at which it can travel through the fluid. This is a simple technique and problems with consistency of results and analysing oils at specific temperatures have relegated it to being a screening only/on-site test.

Kinematic viscosity is a technique which utilises gravity flow capillary tubes to determine the time taken for the fluid to pass between two time sensors. The unit of measurement is Centistokes (cSt - mm²/s), and therefore is very accurate.

Monition's laboratory provides Kinematic Viscosity Testing at 40°C as standard, and can provide testing at 100°C on request.

Monition's laboratory utilises 'Houillon Viscometer baths', which are considered the quality standard within this field. The Houillon Viscometer instrument is basically a temperature controlled bath filled with silicon fluid. The bath contains up to four capillary tubes. The selection of the different size of tubes is based on the expected viscosity of samples to be analysed. A tube constant can be calculated using a standard (of known Viscosity at a specific temperature). If the capillary size is correct for the oil in use, the constant should be between 1 - 3.

Temperature is an important factor when analysing oils for Viscosity. Minor changes in temperature can affect the results achieved. The universal temperature for analysing standard oils is 40°C. The Houllion bath is capable of ramping the temperature up or down to suit the requirements of customers.

In the automotive industry, it is normal for an engines oil viscosity to be carried out at 40°C and 100°C.

The theory behind the two temperature test is to check the oil's performance at different temperatures. The results are then used to calculate a Viscosity index which is an index of the oils performance properties. VI > 100 is good.

In Multi-grade oils, the Viscosity index can indicate a breakdown in lubrication performance and properties. The standard test temperature for the Railways engines is 60°C. This temperature is considered a more representative temperature of the engine.

Further Information regarding Viscosity Testing

Monition can provide assistance in all your Viscosity Testing applications. For further information on Viscosity Testing or arrange onsite alignment of plant machinery, please telephone Monition on 01909 722000. Alternatively you can email us at or complete our enquiry form and one of our sales team will contact you to discuss your requirements.

Safecontractor Approved
Institute of Asset Managment Membership
Railway Industry Qualification Scheme
ISO 9001 Registered

Bondhay Complex, Whitwell Common, Worksop, Nottinghamshire, S80 3EH, United Kingdom
Tel: 01909 722000 | | Company Number: 02218477