Oil Viscosity Explained By Eurofins TestOil

Viscosity is the most important physical property of a lubricant and the most important specification. It's also very easy to overlook. 

A simple definition of viscosity is the thickness of an oil. While this is the most common understanding of viscosity, a more technical definition of viscosity is a measurement of the oil’s internal resistance or its resistance to flow by gravity. Viscosity is what carries the load, separating surfaces in relative motion--thus reducing friction and wear and extending equipment life.

Viscosity should always be measured at a given temperature. Normally viscosity is inversely proportional to temperature, meaning as the temperature of an oil increases, its viscosity generally will decrease.

if you have a gearbox with a manufacturer’s nameplate instructing you to use the American Gear Manufacturer’s Association (AGMA) #4 viscosity oil at a given operating temperature, or if it specified a 750 SSU viscosity oil, would you know exactly what viscosity oil you need? If your grease application specified a base oil viscosity of 220 cSt for a given operating temperature, would you know which of your greases might fit that specification, if any?

The viscosity statistic is found in many different formats depending on the application. The International Standards Organization (ISO) is the universally accepted method for stating oil viscosity (ISO VG) through-out industry (ISO 3448). This ranges from an ISO VG 2 to an ISO VG 3200. ISO VG is stated at 40°C. 

AGMA specify grades an oil’s viscosity for industrial gear applications, also at 40ºC. The AGMA uses a #1 through #8A designation.

SUS - or - SSU is not used much today, but you may still find it referenced on an older gearbox nameplate or an OEM (original equipment manufacturer) manual. This stands for Saybolt Universal Seconds - or - Saybolt Seconds Universal, you’ll see it stated either way.

Society of Automotive Engineers (SAE) Crankcase and SAE Gear classifications are different still: 0W, 5W, 10W, etc., and straight weights 30, 40, and 50 are designations for crankcase oils, while 70W to 85W and 80 to 250 are designations for automotive gear oils.

If all of this makes sense, you are likely on top of your game and know exactly which oils and viscosities belongs in each application throughout your facility. But if this sounds like a foreign language, it’s okay, as long as you now realize that regular viscosity testing by a qualified lab will deliver cost-saving improvements that will greatly enhance your equipment’s reliability.

For more information on working with Eurofins TestOil for Viscosity Testing oil analysis programs or training opportunities, fill out the form below; visit https://testoil.com/company/contact-us/; call 216-251-2510; or email sales@testoil.com.

About Eurofins TestOil

With more than 30 years of experience in the oil analysis industry, Eurofins TestOil focuses exclusively on assisting industrial facilities with reducing maintenance costs and avoiding unexpected downtime through oil and fuel analysis program implementation. As industry experts in diagnosing oil-related issues in equipment such as turbines, hydraulics, gearboxes, pumps, compressors and diesel generators, Eurofins TestOil provides customers with same-day turnaround on routine oil analysis testing.  For more information on partnering with Eurofins TestOil on oil analysis programs or training opportunities visit https://testoil.com. Contact: Al Yates 216-251-2510; sales@testoil.com. 

About Eurofins – the global leader in bio-analysis

Eurofins is Testing for Life. Eurofins is the global leader in food, environment, pharmaceutical and cosmetic product testing, and in discovery pharmacology, forensics, advanced material sciences and agroscience Contract Research services. Eurofins is also a market leader in certain testing and laboratory services for genomics, and in the support of clinical studies, as well as in BioPharma Contract Development and Manufacturing. The Group also has a rapidly developing presence in highly specialised and molecular clinical diagnostic testing and in-vitro diagnostic products.

With over 61,000 staff across a network of 940 laboratories in 59 countries, Eurofins’ companies offer a portfolio of over 200,000 analytical methods. Eurofins Shares are listed on Euronext Paris Stock Exchange.