Approvals Cease for P Industrial Lubes


The laboratory that provided testing and certification for P hydraulic fluid and gear oil specifications has ceased operations, signaling the possible start of a phase-out period for some of the industrys oldest active industrial lube standards.

Fives Machining Systems, Inc., a Cincinnati-based offshoot of the Milacron Machine Group, has closed its dedicated lubricants laboratory and will no longer approve products for its P group of specifications, which cover gear lubricants and hydraulic fluids for machine tools.

Get alerts when new Sustainability Blog articles are available.


The company shut down the lab in September 2018 and informed other companies it was exiting the business of approving lubes and other fluids. “The specifications are primarily focused on thermal stability,” Shubhamita Basu, Lubrizol North America product manager for industrial oils, told Lube Report.

Similar specifications can still provide coverage for companies seeking certifications for their products. “Thermal stability is part of the requirement for the [original equipment manufacturer] specifications like Eaton, Bosch and Denison along with the OEM specified pump tests and many other performance bench tests like seals compatibility, oxidation stability, hydrolytic stability and rust and corrosion protection to name a few,” she explained. So Denison and other specifications issued by the pump manufacturers cover the overall performance of the fluid.

Basu said the P specifications are commonly used and that most oil marketers that sent products to be tested at Fives – the lab also certified for other industrial lubricant specs – sought approvals for the P specs. After reformulating or rebranding products, lubricant producers would submit their new formulations to Fives for testing. As such they often cited our certification in their information and advertising, said Jason Melcher, Fives chief marketing officer.

The list of companies with P spec approvals includes some of the largest suppliers of lubricants and lube additives, such as ExxonMobil, Shell and Chevron Oronite. But not all prominent players obtained them. Basu noted that Lubrizol formulates products to meet a wide range of industrial lube specifications but that none of the companys products are formulated specifically for the P specs.

The specifications were developed by Cincinnati Milling Machine Co., a portion of which is now part of Fives, that portion having been spun off a few years ago by Milacron. Melcher said the P stood for purchase and that the earliest known reference to the P specs is in an operators manual from 1941 for an automatic rise and fall milling machine from Cincinnati Milling. A 1944 lubricants manual from the same company listed the specifications, ranging from P-31 up to P-52. A Fives manual from 2015 goes all the way up to P-81.

“Our understanding is that with the rise in [machine] orders – especially overseas – prior to United States involvement in WWII, a standard was developed to allow a geographically broad and diverse customer base to identify an acceptable lubricant,” said Melcher. P specs essentially were a byproduct of volume, best practices, organization and machine tool and general manufacturing leadership.

Melcher emphasized that the closing of Fives lab does not retire the P specifications but renders them static. Marketers may still market products approved for the specs and promote them as meeting those standards, but new products and formulations will not be able to gain such approvals.

While this could hamper operators of old Milacron machines from identifying new products that would comply with recommendations from their equipment manuals, Melcher emphasized that the industry has other active specs that provide at least the performance of the P specs.

“It is possible to identify lubricants with the identical set of criterion values [as the P specifications] by using the ISO designation,” he explained. “What will happen over time is that as lubricant producers reformulate or retire various trade names, customers will need to reference the ISO/P chart at the front of their manuals to then decide which lubricant is appropriate. Fives will at the same time switch documentation literature of new designs to utilize the ISO designation system rather than the P classes.”

Fives lubricant manual provides an equivalency chart that matches a P specification to its ISO designation counterpart.