Demystifying lubricants. What is the secret to making your lubricating oil last much longer?

Let’s face it, lubricating oil management can be a headache for many reasons.

The price of your lubricating oil seems to keep going up. When it comes to the time of changing there is conflicting advice ranging from always to never changing.

To cap things off there is information overload on what lubricant you should be using to get the best value and machinery protection – is it mineral, semi synthetic, synthetic, PAO, PAG, PE to name but a few. If you read the spec sheets all the oils seem to sound the best with “High performance”, “advanced wear protection”, “extremely thermally stable”, “long life” and a raft of approvals so long it would make a Nobel prize winning scientist’s CV look rather weak in comparison. Heaven forbid you should ever change oil type as then you need to look at compatibility too.

This article will cover a few simple ways to get the most out of your lubricant and how to make it last longer.

Keeping it in and stopping it leaving

It is good practice to monitor the oil level regularly and keep a record of top ups being made. It costs nothing and is very simple to perform using dipsticks or sight glasses as applicable. If your oil level is going down fast and you are having to top up often, that is a cost of lubricant you don’t need to be having if you address the issue. Common causes of increased top up include:

  • Seal leaks – your seals are not always able to take every type of lubricant. When installed they are designed to ever so slightly change shape to give as best sealing as possible and the lubricant assists in doing this – usually by causing a tiny swelling. However, the wrong lubricant can dramatically change the seal causing to over swell and deform or actually cause it to shrink. Both result in leaks. Often your lubricant manufacturer will mention seal compatibility, but this assumes you 1 know the seals in use and 2 your type of seal is the exact same type and not a sub-variant of the ones the lubricant manufacturer tested with. Hence the only true way to confirm if there is a compatibility issue is to send an unused seal and some of the unused oil to your oil analysis lab and ask for a comparability testing analysis. My lab has done quite a few of these types of tests. Generally it is often after the horse has bolted, the system is already leaking and the customer is trying to find the root cause. However, some have been proactive, especially if switching oil supplier, there would be large or expensive oil changes, or the customer is changing oils by top-up (meaning you need to test for a mix of products as well as the two individually) rather than changing oil and flushing completely with new oil.
  • Overheating – fluid volume may not be escaping by leaks and can leave by evaporation of the lighter parts of the oil. This can on the rare occasion be a product issue if e.g. the supplier has mixed a thin and thick oil to achieve the viscosity grade, e.g. mixing a ISO VG 32 and 68 to make an ISO VG 46. This however is often frowned upon and can be spotted on used oil analysis very quickly as a rapidly increasing viscosity of a new oil as the lighter oil begins to evaporate preferentially. Industry checks, new oil specification tests and only using reputable suppliers tend to mean this is something that very rarely happens in the UK market now so the cause is usually something else to be causing oil to be leaving by evaporation. This cause is usually temperature – if the system is running too hot not only does it nominally half the life of the oil for every 10’C rise, but it can both cause boiling off of lighter parts of the oil and also warping of seals. I had a customer who’s average temperature was around 50’C and suddenly had massive volume loss after the system spiked to 90’C. This lead to both a 16 fold reduction in oil life (half for every 10’C rise) with severe oxidation, but also severe and permanent degradation of seals leading to loss of oil by both evaporation and seal leaking. Hence monitoring system temperatures and informing your lab of any temperature spikes or gradual increases can be important in helping prevent system issues. Also monitoring of any cooling system fluids and varnish levels in lubricants, which can lead to system insulation – reducing heat escape, by your lab can help in keeping the temperature to an acceptable level.

Keep it cool and prevent overheating.

I already touched on this in the last point. As far back as the 1800s it was known that the rate of any chemical reaction depended on temperature. This was initially highlighted by a Swedish scientist Svante Arrhenius in 1889. Your oil degradation by e.g. oxidation is a chemical reaction and so governed by these scientific principles. Without going into the mathematics which you can read more about on the Wikipedia link to Arrhenius equation here if you are interested, what it means in practice is for every 10 degrees Celsius increase in temperature, the rate of reaction doubles. This means for every 10’C increase, oxidation by air and hydrolysis by water double, meaning your oil life is halved. Because it is for each 10’C increase, if you increase the temperature by 20’c this means the life is quartered (½ x ½ = ¼).

Funnily enough, when explaining this principle to a customer on a training course I got the response that “yes, but surely this doesn’t apply to my oil – it’s fully synthetic with superb oxidation resistance.” Clearly the marketing team at that customers oil supplier had the customer convinced their oil was so good it defies the laws of physics, but I had to let him down gently and explain the rule applies to ALL chemical reactions. If you are still not convinced by the principle governing all chemical reactions, take this real world examples. For example, you all have a fridge or freezer at home. This is the principle in practice, for instance if you put some food on your work counter at 25’C it may last a day or two before it goes off, whilst in the fridge it could maybe last a week and in the freezer months. Have you ever wondered why? The chemical reactions inside the food causing it to go off and in the microorganisms coating it all go slower when they are cooled down meaning the food lasts longer.

So now you are convinced by the principle, how do I keep my oil cool? I am not advocating attaching a fridge to each of your machines to keep it cool as the oil also needs to be at the right temperature to allow mechanical processes to occur smoothly. The first thing to do is monitor system temperatures and work out do you have any localised hotspots or higher than average temperatures. Then comes the point of working out why the temperature is high if it is higher than usual. This can fall into a few key areas:

  • Inadequate cooling – if the system has a dedicated fluid cooling system such as cooling water or glycol based coolants it’s worthwhile doing regular sampling of these to ensure the cooling system is kept in tip-top condition. In fact ~80% of all engine failures are found to be cooling related so you can get some useful information by sampling not only your oil but your coolant as well.
  • Too much insulation – that’s right your lubricant degradation products can be actually insulating your system keeping it hot and increasing the rate of degradation. A common cause of this is the oxidation material called varnish which is sludge-like material that forms as the lubricant degrades. Now this happens at the hottest parts of the system and especially at any localised hotspots, but because the lubricant is warm it remains dissolved in solution. However, as the lubricant cools such at the parts of the system designed to remove heat like oil coolers, this varnish precipitates and over time forms an insulating layer reducing heat loss from the system. This is a vicious cycle as it generates more heat which generates more varnish which insulates the system more and so forth. Regular monitoring of your lubricant condition can help reduce the risk of varnish formation and identify the lubricants tendency to varnish often called its varnish potential.
  • Too thick a lubricant – since moving parts have to pass across the lubricant film surface, friction is generated (much less than metal to metal contact but there is still friction) between the lubricant and the the machinery parts. If the oil is too thick the drag is increased and excessive heat is generated as the system has to work harder to move through the thicker lubricant. Ensuring you choose the lubricant that is right for your machinery and regularly monitoring viscosity as part of your oil analysis programme help ensure this doesn’t become an issue for you.
  • Wear hotspots – wearing components especially when severely abnormal can generate heat from the severe friction. You only have to rub your hands together fast for a few seconds to realise how quickly heat can generate from two surfaces rubbing together. Heat generation is usually one of the later stages of wear and perhaps your concern is more the machine than the cost of an oil change at this point, but in the total repair cost, the cost of oil change should be included too. Regular oil analysis and particularly use of the LubeWear technique mean you can detect the very earliest stages of abnormal wear even without trending. This means you not only can help improve machinery life, but can help reduce the chance of a hotspot developing in the first place by addressing the wearing component cause early.

Keep your oil clean and dry

Apart from the fact water is a poor lubricant and leads to corrosion and wear in your machinery, it also can greatly reduce the life of your oil. For example many additives within the lubricant can be either hydrolysed (i.e. chemically broken down by water) or simply washed out of the oil as they preferentially dissolve better in water than the oil. This leaves your lubricant greatly hindered in its ability to keep your equipment healthy. Equally, as an oil oxidises it forms acids, but for an acid to work it needs to be wet so it can dissociate the Hydrogen ions (the bit that give the low pH of an acid). Hence high moisture in the oil helps organic acids work better at corroding machinery parts and equally at causing further oxidation of the lubricant. Hence reducing water content in your oil through preventative measures and removal methods gives your lubricant the best chance of reaching its full potential life.

Likewise, particles in the oil such as dirt and wear also reduce the life of the oil. For instance, many contamination particles are attacked by the oils protective additives such as detergents, dispersants and anti wear additives (for wear particles) meaning when they reach the oil filter they are filtered out and depleted from the oil. This is a normal process, but the more particles in the oil the faster the depletion of these additives. Equally, wear particles cause oxidation because particles such as iron are catalysts for oxidation reactions, meaning buildup of wear material at the bottom of your lubricant tank can actually be accelerating the rate of lubricant degradation. What’s more is that if you don’t fully remove those particles during each oil drain they build up over multiple oil changes and increase the rate of degradation of all future oils used.

“Stop oil loss, keep temperatures in the ideal range, keep it clean and keep it dry are the secret to a healthy machine and healthy oil. Most of oil sample the machinery to check its health in the first place.

So keeping your oil clean and dry is a key way to protect the machinery, extend oil life and the best way to check this is through testing it. This brings me onto the final way to extend lubricant life and that is actually testing the condition of your lubricant.

Check your Lubricating oil

This may seem a strange last stage, but hopefully you have understood that taking an interest in the condition of your lubricant is the best way to extend its life. Sampling the lubricant and the fluids that interact with it such as fuel, coolant and Adblue/DEF are all key to ensuring your machinery has the best fluid health and the longest life in terms of lubricant and machinery components. The simplest way to achieve this is to take an an oil sample. A typical analysis from my lab tests between 50 and 60 different parameters on each and every sample so you get a full fluid assessment in a few easy steps. You can support this with good lubricant management such as storing your lubricants correctly, monitoring fluid levels and temperatures in addition to performing the service activities at the correct times. Fluid analysis will never replace the need to maintain machinery, but it can help you focus your efforts on the areas that need attention most after each sample extending both your machinery and lubricant life.

If you would like to find out more about how you could be saving money on machinery fluids, repairs and downtime costs then click the contact us button at the bottom right of this page. Alternatively, if you would like to calculate the savings you could be making with oil analysis then try our cost saving calculator here.