What’s it like living on the edge of a specification when there is no grey area, just the nasty precipice of pass or fail? A classification cliff-edge if you like. Most lube manufacturers play it safe and blend to the midpoint of the spec to give some wriggle room for error, but some have clearly got balls of steel, four-balls of steel that is (before I hear sniggering in the back, four ball is an actual test see below. )
As I already made a pun regarding this test I thought it best to explain it. In the Four Ball Test, three steel balls sit still while a fourth rotates against them in the lubricant under test. The test measures how much the rotating ball wears down. These are literally balls of hardened steel. The Four Ball Test is an important tool for evaluating lubricants for new oil specification testing, and with it, scientists and engineers can determine which ones have the balls to protect against friction and wear.
Testing with balls of steel
Anyway I digress. So why might someone only blend to the edge of a spec. There are few reasons why they might.
Covering multiple specs
This is very common in engine oils. Naturally oil suppliers want to meet as many specifications as they can, some of which are often in direct opposition to each other. You can’t blame them really, as the more specs on the side of a oil bottle the better it looks. It’s like when you see a lawyer or a doctor, you feel comforted by all those letters after their names and certificates on the wall behind their desk. You don’t necessarily always know what they all mean, but they must be good surely? Equally for those who do read the approval list carefully and buy to the spec, if you can have your oil scrape into as many different specs as possible by playing some sort of contortionist twister game then all the better to increase your sales. Now apart from a couple of niche suppliers most lube oil suppliers play this game. Unfortunately with a pass / fail scheme there is no way of telling did an oil just scrape through or did it actually pass with flying colours. Some manufacturers will try emphasise this by using words like exceeds rather than meets but on the whole many of these terms are still rather subjective and prone to marketing hype.
Confusing product code type names
Many lube manufacturers tried to add numbers at the end of the products that had no relation to the viscosity grades the products actually were, making it exceptionally difficult for end consumers to pick an oil themselves and they ended up having to rely on their oil suppliers to tell them what they need. This trend stopped in the early 00s with manufacturers returning to word based endings like Max, HD, premium, plus etc, but there are some ranges still using these weird number based names such as Mobil Rarus 824, 827 and 829 which are iso VG 32, 100 and 150 respectively. However, pretty much every major has some quirky product names on their books. These if you dug into the data sheets were actually blended to the mid point of the specs so not necessarily on the cliff edge but just confusing.
Names that sound like grades, but are not
Values like 824 quickly can be dismissed as not being a grade however, there are instances where the grades sound very much like a real grade but are not. This is where oil manufacturers use names for products that sound like a grade but are in no way related to a grade and would actually fail those grade limits. The most classic example is Petro Canada Reflo 68A. Although a very popular product and a I hear nothing but good reviews from its customer base, I am yet to find a user of this product who doesn’t think it’s an ISO VG 68. So much so I have had customers complain we have not filled in the grade field with 68 on our reports testing this oil. It seems so close to an ISO VG 68 in the name doesn’t it? However it’s actually a 59 and the grade isn’t 68, it’s 68A, which for some reason equates to 59 in the PC marketing department. I used to look after the PC account in an old job and it was for them too a difficult question to answer why they came up with this naming convention as it caused a lot of confusion. If anyone from Petro-Canada reading this article knows please write in and I will update this article with the explanation as it would be great for our readers to know.
Actually blending to the edge
Apart from the engine oils achieving multiple specs the rest of the examples I have given have all been weird makings rather than bending to the edge of the spec. Indeed the engine oils example the blending to the edge is not by design and is just a case of trying to cover multiple specs. However, would a lube oil company really want to blend to the edge of the spec not for trying to cover a spec, but for some other reason?
Well the answer is in fact yes. The answer is usually about energy efficiency and the use of synthetic lubricants. So how does that work?
Well we think of viscosity grades being a constant such as 32, 46, 68 etc. However, that is an arbitrary viscosity based on a measurement at 40’C. It makes sense at this temperature but what if your oil is 20’C, 30’c or 50’c. That’s a big change in temperature and depending on the oil you potentially have a big change in viscosity too and hence lubricant film thickness and wear protection. So Joe running his machine 10 hours a week is likely going to be working at a different operating temperature range and film thickness than Bill working his machine 18 hours a day 7 days a week. One will likely have a wide temperature range as it starts and heats up whilst the other with no respite will likely have overall much high temperatures. Neither anywhere near the measured 40’c. The lower temperatures will be thicker with more drag and less energy efficiency, whilst the other will be thinner and giving less film thickness and potentially wear more. You need a goldilocks zone of film thickness not too thin or thick. The problem is this can be a very fine window.
The key to this question is the VI or viscosity index. The higher the VI the more stable the oil is to temperature changes. This gives a different question to oil blenders, rather than setting an ISO grade value at the midpoint they may work more on film thickness required at potential operating ranges. This approach allows the manufacturer when supported with a high VI base stock to blend to a specification edge or even outside of it as they have the comfort blanket of the wriggle room of the VI.
This means these formulations can target both energy efficiency with an overall thinner oil but the higher VI to stop the oil going not as thin as fast. This type of protection is also the same reason you see some synthetic 220s replacing mineral 320s in gearboxes on occasion.
So the question in this case is not why risk the abyss of a spec cliff edge, but why wouldn’t you if you have a safety net right beneath you of a high viscosity index keeping your film thickness and footing stronger for longer.
Just as those extreme climbers dare to go where others fear to tread, when interviewed these climbers find the experience quite zen and not a risk as they have carefully planned every single step, they are not stepping into the abyss, but instead placing their feet and hands exactly where they had planned in detail, with the ropes carefully checked before the journey. Just like this very brave oil blenders blend right to the edge confident in their blending ability to get it right where they want it, albeit sometimes a pain to those trying to classify the lubricant.
What to do when you live near a cliff edge?
The thing with these cliff edge of specifications there is no wriggle room and although the oil may be blended right on that edge, they hand it to the end user and often that’s it until a reorder. Imagine being at the cliff edge and then being handed the ropes to try yourself. The product worked when it left the factory, but those ropes a year or two later look surprisingly frayed. Would you risk it? Well the secret is you don’t need to. Used Lubricant testing can tell you you are getting too close to the edge and help pull you back from the brink before it’s too late.
To find out how oil analysis can help you contact us using the contact button below. We can monitor of your condition of your oil to confirm when it’s getting to the point to change or when things are starting to be a problem before they do and cost you money.
