With Euro-6 in full swing, should fleet managers look more closely at the oils they’re using? Trucks makers certainly are, and one has taken the plunge by setting a new benchmark in low-viscosity lube.
The value of the correct oils in drive trains is not lost on fleet managers, but after the first fill, what should it be replaced with? The demands of Euro-6 make fully synthetic low sulphated ash, phosphorous and sulphur (SAPS) oils inescapable. Most fleets use them, and take the benefit of long drain intervals, while others see economies in using lower quality oil with more frequent drains.
With six-weekly inspections bringing vehicles into workshops with predictable regularity, downtime isn’t affected. Some fleet engineers will not easily part with around £300 to fill a heavy tractor, but it could be short sighted if that oil is contributing to fuel economy. If the oil is ‘at work‘ for 150,000km, it’s only an outlay of 0.2p per 100km.
Since multi-grade oils arrived, they have been managing a delicate balancing act between fuel economy and wear protection. High-viscosity oils protect the engine, but also absorb too many ergs in churning losses and energy-sapping cold starts.
Low-viscosity oil is less of a drain in winter (the ‘W‘ in a 15W-40), but will it consistently keep engine internals from making direct contact at 150ºC?
Last December oil company Petronas launched the lowest viscosity oil yet for a heavy-duty diesel engine, Urania Next 0W-20, which is now standard in Iveco’s 11- and 13-litre Cursor engines. Launched at the unveiling of Iveco’s Dakar rally truck entries, it couldn’t put a more confident stamp on the oil’s ability to take punishment.
Andrea Dolfi, Global OEM Liaison & Motorsport Manager, Research and Technology for Petronas, is confident it stands up to scrutiny. “This is now standard fill for Iveco heavy product, bringing better cold start performance, cutting the time an engine takes to reach operating temperature, vital for reducing wear and tear.”
Low-viscosity oil provides an advantage for cold starts and fuel economy, with reduced drag losses, but the bigger question is how the oil performs at working temperatures for extended periods – the ’20’ bit of the 0W-20.
Iveco has extensively tested the oil in its Cursor engines, while Fiat showed confidence when it brought Iveco’s Hi-Efficiency selective catalytic reduction engines to the market for Euro-6, eschewing any assistance from exhaust gas recirculation, which was almost universally adopted. So far, no other manufacturer has recommended such low-viscosity oil.
All oils claim a fuel economy advantage, but Euro-6 engines are not just Euro-5 with extra plumbing, they represent the tightest manufacturing tolerances, and the engineering quality should be matched by the oil spec. Operators that develop a taste for cheap oil should think again, as the essential diesel particulate filters in Euro-6 engines will not tolerate poor quality oils.
Steve Crawley, Global Strategic Marketing Advisor at ExxonMobil Fuels and Lubricants says, “Only low SAPS oils that have a maximum ash content of 1% are suitable for use in Euro-6 trucks. To meet emissions targets, all these engines incorporate exhaust after-treatment devices that are sensitive to lubricant components.”
The only way to establish advantages over an existing brand is to run a trial, with as many variables as possible eliminated. Crawley says, “Our Signum oil analysis helps extend equipment component and lubricant life, provides early warning signs of contamination and minimises unscheduled maintenance.”
There’s no magic bullet for Euro-6 oil choice. Scania GB’s Technical Manager, Clive Burnet said, “The question of what oils we use in a Euro-6 truck doesn’t have a simple answer. It could be one of dozens, depending on the model and the operation.”
A mixed fleet with a range of duty cycles generates a wide range of oil specifications. Transmission oils may work at lower temperatures, but often suffer from user complacency. Like all components, oil wears out and as the chemistry breaks down, it costs efficiency and money. Gearbox rear axle oil has a limited life and the chemicals involved are sulphur-phosphorous based, which leave deposits on the gear teeth to cut friction losses.
Although Euro-6 has developed a taste for fine oils, walking the tightrope of oil viscosity and specification has potential wins. Get it right, and there are fuel savings, as well as a subtle horsepower benefit, while getting it wrong could be expensive at around two pence per 100km.
