A technical data sheet (TDS) provides key information about a lubricant. This includes how it performs under different conditions. As a result, a TDS is an important resource that informs correct lubricant selection for an application.
Typically one to two pages in length, a TDS isn’t a legal document. It’s a marketing document designed for technical people. Companies like Shell, Castrol and Mobil select details to include on these sheets so that the data supplied can vary between manufacturers. However, you can still compare product data from different companies, providing you understand the general data fields listed.
Here, we break down the fields and terms found in a TDS to help your understanding of the data they contain to make an informed decision when ordering lubricant.
Product information
Technical data sheets start by listing the brand and product name, followed by a unique product code. This identifies the lubricant.
They also supply a description of the product with a varying degree of detail. They will list the lubricant type, like oil, grease or hydraulic fluid, and list its main features and benefits. More detailed descriptions may include the lubricant’s composition to explain how it performs.
The lubricant’s intended applications are also listed. This cover environmental factors, operational conditions and compatible equipment that the oil or grease was designed for.
Viscosity
A key element of lubricant selection, data sheets always include information on viscosity, which measures a product’s resistance to flow. The viscosity index (VI) number shows how much an oil’s viscosity changes at different temperatures. Higher VI numbers mean better performance at a wider temperature range and less viscosity change.
SAE Grades for oils describe a lubricant’s ability to flow at varying temperatures and classify oils into summer and winter grades based on how thin or thick they are when hot or cold.
Monograde oils have a single viscosity rating (e.g., SAE 30). They are suited to specific applications, such as seasonal gardening equipment like lawnmowers or in classic cars engines, while multigrade oils have a two number viscosity rating (e.g., SAE 10W-30) and see use in modern cars.
The term ISO Viscosity Grade is also referenced on TDS for oils. This is a system from the International Organisation for Standardisation (ISO) and classifies lubricating oils by rating their kinematic viscosity at a temperature of 40°C.
Grease-specific terms
Often designed for different applications, greases are thicker than oils and designed to remain in place rather than flow. As a result, they have a National Lubricating Grease Institute (NLGI) classification. This grade, which ranges from 000 (semi-fluid) to six (block of soap) indicates consistency and is key for ensuring correct application. Products with a higher NLGI number are thicker, more solid greases.
The lubricant dropping point is also detailed in the TDS. This indicates the temperature where a lubricant, especially a grease, turns from being semi-solid to liquid.
Performance properties
On a TDS, specific gravity shows lubricant density relative to water. This is a critical physical property that impacts a lubricant’s handling, performance and water separability and miscibility. It shows the weight of the product per unit volume at a certain temperature.
Pour points are provided for oils. This is the lowest temperature that the lubricant remains pourable at and flows effectively.
Data sheets also include information on oxidation stability to show a lubricant’s resistance to degradation due to oxygen contamination. This property is crucial to determining a product’s expected performance and service life under high heat or pressure.
The total base number (TBN) is provided for engine oils. It shows the lubricants capacity to neutralise harmful acids generated during combustion, expressed in mg KOH/g. The higher the number, the greater its alkalinity and the more additives it offers to protect against engine wear and corrosion. A lubricant’s flash point is also listed, showing its relative flammability.
Four-Ball Wear Test results are often supplied for oils
This test predicts the wear protection properties of the lubricant. It provides an indication of how well a lubricant protects against abrasive wear over time. The shorter the length of the scar, the better the protection. For instance, 0.5 mm is outstanding.
Specifications and approvals
Finally, lubrication technical data sheets provide details on the standards they meet and approvals they carry. This allows users to check that products adhere to the standards of the American Petroleum Institute (API) or the European Automobile Manufacturers’ Association (ACEA). Furthermore, some lubricants have also been approved and tested by original equipment manufacturers (OEMs).
