Lubricant Technical data sheets (TDS) are often presented as the ultimate guide to understanding a lubricant. However, after reviewing thousands of these documents over the years, I have learned that they are not always as transparent as they seem. This article will help you break through the marketing jargon, identify key details, and truly understand what the data is telling you.
Product Information: Marketing in Disguise
The first section of a technical data sheet typically provides an overview of the product, detailing its intended applications and highlighting its key benefits. If you’ve ever read one, you’ll notice a pattern: phrases like “excellent performance,” “superior protection,” “enhanced durability,” and “improved efficiency” are common. While these terms sound promising, they are inherently subjective and should not be blindly trusted. Equally since every lubricant TDS uses these phrases and I have never heard phrases such as “Poor” or “Average” used it can be hard to distinguish anything useful from a section full of superlatives. They do not provide quantifiable proof of superiority; rather, they serve as marketing tools designed to make the product sound like the best choice. Their job is purely to make you buy and treat it like you would any advertisement or brochure you read.
What You Should Focus On:
Instead of getting caught up in these claims that cannot be verified, look for:
- Where the lubricant is NOT recommended. Some TDSs will explicitly state limitations, but many do not. Be wary of the absence of warnings. Ultimately the job of a TDS is to make you buy and lube suppliers want as much coverage of their lubricant as possible. So you can trust when they say where it can’t be used because that is hurting a sale for the company.
- Compatibility concerns. If the lubricant mentions incompatibility with specific materials or applications, take note. Usually changing from one oil to another where there are compatability concerns is a real pain for end users and can be a blocker for a sale. So if the oil company is listing any potential extra work you need to do it is highlighting potential risks and also helping cover them from potential litigation in future.
- Base oil and additive composition. Some manufacturers may not disclose these details, but if they do, it can provide valuable insight into performance and compatibility.
Approvals: Are They Relevant to You?
Many TDSs include a section listing various industry approvals and certifications. These can be useful, but they only matter if your equipment requires them for warranty purposes. For example, an API SN approval is important for passenger car engine oils, while an ACEA E9 rating is critical for heavy-duty diesel engines. Similarly, some OEMs (Original Equipment Manufacturers) issue their own approvals, such as Mercedes-Benz MB 229.51 or Volvo VDS-4.5.
How to Interpret Approvals:
- If your machinery requires a specific approval, then it’s essential that the lubricant has it.
- If an approval is missing, do not assume the lubricant is unsuitable—it may simply mean the manufacturer has not sought certification.
- Some approvals require periodic re-certification, so ensure that the approval is current and valid.
The Tests: What They Say and What They Don’t
The most valuable part of a technical data sheet is the test data. However, manufacturers often selectively highlight strong points while omitting less favourable results. Here’s how to read between the lines.
Neutral Tests: Neither Good Nor Bad
Some tests provide baseline information but don’t indicate performance quality. Examples include:
- Density (kg/m³) – Tells you the weight per unit volume but does not affect lubrication quality.
- Viscosity Index (VI) – Higher VI suggests better viscosity stability across temperature ranges but does not always mean better performance.
- Flash Point (°C or °F) – Indicates volatility but does not directly correlate with lubricant longevity.
Selective Tests: What’s Highlighted vs. What’s Missing
Manufacturers often emphasize areas where the lubricant excels while remaining silent on potential weaknesses. For example:
- If the TDS boasts excellent oxidation stability but does not mention shear stability, it may mean the lubricant breaks down under mechanical stress.
- High TBN (Total Base Number) is often praised for acid neutralization, but the SAPS or sulphated ash is likely to be higher and brings in return its own issues.
- Wear protection tests (e.g., Four-Ball Wear Test) may be highlighted, but extreme pressure (EP) performance may not be disclosed if it performs poorly.
- Tests that are not key to your application. For instance a gas engine oil with a really low pour point may not be a key factor if your machine is in a hot climate. Likewise a high VI is likely not relevant if your operating temperature never varies.
Key Takeaway: Look for Omissions
The most telling part of a TDS is often what’s not included. If a crucial performance parameter is missing, assume it is either untested or the results were unfavourable.
One thing I found recently when doing some research with our cold cranking simulator (the test that determines the W part of engine oils) was how many manufacturers of engine oils don’t quote a typical cold cranking viscosity value. I had about 20 major manufacturers 5w30 products on our shelves (as we often stock various lube oils for our own research) and only 3 of them stated a value on the spec sheet.
Why Regular Oil Analysis is Essential
The most important thing to understand about a technical data sheet is that it only represents the lubricant at the time of production. Once the oil enters your machine, everything changes. Contaminants, oxidation, mechanical stress, and temperature variations alter the lubricant’s properties, making the original specifications irrelevant.
Routine Oil Analysis Provides Real-World Data
The only way to truly understand how a lubricant is performing in your equipment is through regular oil analysis. Here’s why:
- Degradation Over Time: Lubricants oxidize, shear, and lose additive effectiveness, affecting performance.
- Contamination Detection: Wear metals, water, and debris accumulate, influencing lubricant efficiency.
- Early Failure Prevention: Monitoring trends in viscosity, acidity, and additive depletion can prevent costly breakdowns.
A technical data sheet is merely a starting point. To ensure optimal machine performance, ongoing oil analysis is the only reliable way to assess lubricant health.
Case study
Last month we helped a customer in selecting a new fire resistant lubricant. They had several manufacturers bidding on the price but an independent lab was required to assess the technical aspects. Around 15 oils made the original short list and this was wound down to 9 we finally tested (I’m presuming on commercial aspects).
What was interesting is manufacturers love giving greater figures which on things like flammability tests or ranges so we saw eg >350’c or 400 to 500 etc on other tests. However we found for instance on autoignition the >350 was around 375 on one product but another of >350 was actually 450. So quite a large difference.
Another aspect was during testing you happen to find certain things by accident such as when checking seal comparability at high temperatures one lubricant almost evaporated after a week meaning topup rates were going to be more of an issue with that product, which isn’t something you really see on the data sheets and can be a big influence on costs of lubricants used even if the price per litre is better.
Overall the cost of the lubricant supply tender was £3m over 5 years. So it’s worthwhile spending a fraction of that on testing the shortlist of candidates to select the right lubricant for your application. Indeed many of the tests that suit your application won’t be listed on any spec sheets so that’s why it’s important to start the discussion with a lab early in the procurement cycle.
Final Thoughts: Read with a Critical Eye
When reviewing a technical data sheet, keep these key points in mind:
- Ignore marketing terms like “superior” or “excellent” and focus on tangible specifications.
- Look for limitations and incompatibilities, as these are often more informative than strengths.
- Only care about approvals if they are relevant to your equipment.
- Pay attention to omitted test results, as they may indicate hidden weaknesses.
- Remember that a TDS is just a snapshot in time—regular oil analysis is the only way to ensure ongoing performance.
By adopting this analytical approach, you will gain a deeper understanding of lubricants and make better-informed decisions for your machinery’s lubrication needs.
If you need help selecting a lubricant from an independent expert, visit Learn Oil Analysis or click ‘Contact Us’ for professional guidance.