Understanding Fleet Engine Oils
Truck Lubricants

As we have seen in previous posts, engine oil is an essential item when it comes to the health and performance of your vehicle. Choosing the wrong or an inferior product can lead to catastrophic and sometimes irreparable damage to your engine while on the flipside, a superior oil can extend life and increase efficiency. This is extremely important in the everyday operations of your fleet as it is imperative that your trucks on the road at all times and do not compromise your companies productivity.


But as we have seen with automotive engine oils, it can be extremely confusing to decide what the right product is for your vehicles. Numerous specifications and accreditations are found on the packaging and technical details on its data sheet. Another issue can be the terminology. Is the oil a long drain product or a Euro 7 engine oil? The default answer to this is we look at the price and in the short term this may seem like the right answer. But long term, other factors come in to play.  Drain intervals, the reduction of downtime, engine oil capacities, filtration costs and fuel-efficiency issues to be considered.


Fleet managers, especially those that have their own in-house service team, have an excellent opportunity to explore a wide range of options. Depending on the size of their fleet, they can buy oil in bulk at competitive pricing, while ensuring that the other key product benefits are to their best advantage.


But before looking at these areas there is 1 key item we have left out; the OEM manual. It is extremely important that you get the technical aspects correct and the first place to start is the manual. Engine oils must meet the specifications laid out by the OEM or there is a high risk of invalidating the vehicle warranty.

European Emission Standards

These standards highlight the acceptable range for exhaust emissions of new vehicles that are sold within the EU. Faced with concerns around global warming, the EU created these standards to help make trucks and buses as clean and effective as they can be in a bid to reduce everyday pollutants such as CO2 and other particulates. The table below highlights the Euro Standard and when it was introduced:

Euro Standards for Heavy Duty Diesel Engines

Understanding the Oil specifications

The European Automobile Manufacturers’ Association or ACEA define oil specification that is known as ACEA Oil Sequences. Updated every 4 years (the most recent being 2016) heavy-duty engine oils are indicated by an “E”. In the case of the “E” classes, a number will also define the category. We will look at these categories below:


Considered “stable” the key characteristic of E4 oils is their emphasis on a high level of detergency, reducing the build-up of combustion 

 rated oils.

deposits on pistons and excellent control of cleanliness. Although they are not low-SAPS oils and are not recommended for vehicles with DPF, E4 products usually have either partially- or fully-synthetic oil or at least, the very highest-rated (group III) mineral oils. For this reason, E4 oils would be more expensive than your regular mineral based formulations.


Ultra-high-performance diesel lubricants (UHPD), E6 lubricants are specifically designed for use in long drain applications operating in severe conditions. Very similar to E4 engine oils, E6 has the extra benefit of low-SAPS for vehicles that have a DPF and are considered high


An oil that suits the majority of current engines as long as they do not have a diesel particulate filter (DPF) in their exhaust. Usually a mineral based engine oil they would be cheaper than low-saps oils… These factors make it one of the most popular sequences in the Irish market today.



These oils are extremely similar in application to E7 oils, but with one important exception – they have tight limits for sulphated ash, phosphorus and sulphur. They are considered low-SAPS oils and are designed specifically to suit trucks that are built with a DPF in the exhaust: low-SAPS oils produce less ash when they burn, so the DPF needs cleaning less frequently.  Although still mineral-based, E9 oils need a low-sulphur base oil that differs from the group I base oil used for E7 oils, which would make E9 more expensive than E7.


Manufacturer Specifications

To make things difficult, truck manufacturers also have their own unique oil specifications that run parallel alongside the ACEA’s sequences. For example, many E7 oils have Renault trucks RLD-3, Volvo VDS-3 or MAN M 3275. Similarly, E9 oils can often meet Volvo VDS-4 and Mercedes 228.51 specifications

The majority of premium oils are so well formulated that there is specific areas area where they will overlap. For example, many E6 oils also meet E4 and E7 specifications and have a number of manufacturer approvals. This is particularly useful for operators of a mixed fleet where there is a potential of using the wrong oil.

ACEA Engine Sequences

What are LOW-SAPS engine oils?

Diesel Particulate Filters (DPF) have a huge effect on the type of engine oil that can be used in your truck… When the combustion process in an engine occurs, a small amount of oil is burned off. The parts of the oil that are burned off could quite quickly clog a DPF which could cause numerous issues. This is why low-SAPS or low ash oil is needed.

So if your truck has a DPF, your engine-oil choices fall to either an E9 or E6. Again this will be decided by what the OEM manufacturer recommends as the most suitable oil for your engine.


Drain Intervals: A Key Cost-Saver

Longer drain intervals are a huge benefit to fleet operators. Downtime is reduced and a number of costs drop as service periods decrease along with labour costs. But what factors influence drain interval periods? Most manufacturers approximately 60-70,000km operating within Ireland, reduced to 30-40,000km in severe environments such as short distance urban or construction work but extended to maybe 80-100,000km on long distance and lighter duties. Fuel consumption can be a good indicator when it comes to drain intervals.  Higher than average fuel consumption would usually align with tougher demands on the oil.


One of the main factors restraining engine-oil life is oxidation. This is the gradual acidification and degradation of the oil; new oil is alkaline in order to combat the acidity of the combustion. Once an oil’s reserves of alkalinity are severely depleted its ability to resist engine wear is also depleted. Taking oil into this danger zone by delaying a change is risky but one many fleet managers take due to the perceived savings on oil changes. Semi- and full-synthetic base oils are better at fighting oxidation than mineral base oils, explaining why truck manufacturers specify that synthetic-based E4 and E6 oils are essential if operators want to take drain intervals out to the maximum, sometimes as high as roughly 120,000km under the right conditions.


Typically, synthetic base oils have a much higher viscosity index than mineral oils. That means they are more resistant to thinning at high temperatures and to thickening at low temperatures. They are able to retain this characteristic longer than mineral oil with added viscosity improver. Consequently, they stay closer to their original viscosity for longer, stretching their usable life.


It is up to the operator to calculate whether longer drain intervals validate the premium cost for E4 and E6 oils, taking into account the savings on filters too. As a rule, extended drain intervals only make real sense if they delay the change by at least one scheduled safety inspection.


The Importance of Oil AnalysisOil Analysis

When first attempting to extend oil drain intervals it is essential to use some form of oil sampling to verify how far it is safe to go. Sampling will highlight a number of areas regarding oil life, including how much oxidation has occurred, as measured by the TBN (total base number). Other than planning maintenance operations Oil analysis has a number of benefits including:

  • Reduce operating costs
  • Anticipate and plan maintenance operations
  • Increase equipment lifespan
  • Improve equipment reliability and performance
  • Optimise oil change frequency


How Much Oil is consumed in Modern Engines?

Oil consumption of around 0.075 per cent of fuel consumption is estimated to be typical for a modern heavy-duty diesel engine. A comprehensive approach to engine-oil management includes monitoring the daily use of top-up oil in order to spot engines that are over consuming or unhealthy. But first, we need to identify what is considered regular oil consumption? Euro-1 engines of 20 years ago regularly would use up oil of between 0.1 and 0.15 per cent of their fuel consumption, even in optimum condition.

But burnt engine oil is a source of exhaust particulates so vehicle manufacturers have worked hard to regret a hold on consumption in order to comply with increasingly stringent and demanding emission limits, especially as climate control becomes a bigger issue. Healthy Euro-4 and -5 engines on average should consume oil at a rate no greater than 0.075 per cent of their fuel consumption. So, for example, if a fleet consumes 100,000 litres of fuel each month, top-up oil used in the same period should not average out at much more than 75 litres unless there is an extraordinarily high amount of older trucks.


Fuel-Economy Engine Oils

Operating conditions and cycles are a major influence on the cost-effectiveness of low-viscosity oils designed to save fuel.  But some fleet managers think in the short term and see that these fuel-efficient oils can costs up to 2 or 3 times as much as mineral oil. Therefore, it is the utmost importance to be able to explain and highlight, firstly how fuel economy engine oils work and secondly, the long term benefits to both your costs and your fleet.

The improvement in fuel economy is mainly created from a reduction in viscosity. Thinner oil offers less viscous drag and is circulated around the engine quicker during a cold start, reducing friction and wear immediately. Traditionally, SAE viscosity rating for diesel engines in trucks had been an E7 15W-40. On the other hand, fuel-efficient oils are usually 5W-30 and featuring synthetic base oil. The 5W part of the highlights that the oil will stay thin in low temperatures, helping with cold starts. The 30 showing that it will also stay thin at high temperatures compared to a 15W-40.

Because the engine spends the majority of its time operating at hot temperatures, the second number in the viscosity rating has a greater influence on fuel economy. The limiting factor is those vehicle manufacturers refuse to sanction oils that are too thin at high temperatures. Thin oils leave a thinner film on wear surfaces such as camshafts and bearings: if it is too thin the film shears. Synthetic base oils have a specific formulation that gives them greater film strength compared to mineral oils operating in these high temperature, high shear (HTHS) conditions.


This need for adequate engine wear protection at high-temperature means ACEA sequences include an HTHS viscosity limit that effectively restricts oil to high-temperature viscosity ratings to no lower than 30 for fleet engines, capping the fuel efficiency potential at typical operating temperatures. Fixing viscosity at high temperature puts the emphasis on low-temperature viscosity. Going lower helps here too but the net benefit naturally is dependent on the frequency and need of cold starts which would be extremely rare in countries such as Ireland.


All this explains why the economic benefits of fuel-efficient 5W-30 oils are variable but advantageous. Economy gains of 2.0 to 4.0% are normally quoted: not all such oils are created equal and much depends on the baseline used for comparison Gains are highest in percentage terms when a vehicle is stationary with the engine idling because there are no aerodynamic or rolling resistance losses, so a reduction in engine losses counts for more. Low ambient temperatures and cold start naturally enhance the benefits of thinner oil.


There are many variables to be considered when deciding to switch to a fuel economy oil. It is extremely important to remember that today’s engines have a wide range of needs when it comes to lubrication. Again always consult your owner’s manual or speak to the OEM manufacturer to find out not only the suitability but the expected performance levels when it comes to the right engine oil. Taking a risk when downtime is the biggest cash flow leakage means that using the right engine oil and lubricants, in general, is essential.


Total Rubia RangeRubia Optima

As we have seen, commercial vehicles are faced with extreme driving conditions on a daily basis in an industry where downtime is detrimental in regards to operating costs. Chosen by OEMs, Global Partnerships and long-lasting co-operation with major truck manufacturers across the globe, the Total Rubia brand has earned a reputation for quality and reliability. OEMs put quality and brand re-assurance at the heart of their purchasing decision.

All Total Rubia lubricants are manufacturer-approved, meet the needs of multi-vehicle fleets, and are designed to comply fully with the ACEA and API specifications and environmental demands of the latest generation of diesel engines conforming to EURO I, II, IV, V and VI including EGR, SCR and DPF engines.

With increasing pressure to use the correct oil specification tailored to each engine, it has become more and more difficult for fleet managers to gather all the information required to make the correct product selection. Total aims to ensure fleet managers are aware of changes in engine requirements and therefore changes in engine oils, so they can select the right Total Rubia products.

Total has close partnerships with major truck manufacturers around the world and develops high specification lubricants that fulfil the needs of today’s heavy-duty commercial vehicle sector, while also researching and developing innovative new products that will cater to the needs of this sector in the future.

To find out more information about Total and its product range contact their authorised partner in the Republic of Ireland, Finol Oils at 01-455 5484 or email: [email protected]  or visit www.finol.ie

Finol Oils, 3 Stannaway Drive Crumlin Dublin 12 | Tel:+353 01 4555484