Lowering viscosity without increasing wear
By Tom Jackson
For most of the last decade oil companies have been formulating and reformulating their heavy-duty engine oils to keep up with the changes wrought by emissions regulations.
First it was exhaust gas recirculation technology. EGR caused engines to run hotter and dumped large amounts of soot into the combustion chamber. Then to further clean the air, the Environmental Protection Agency forced oil companies to drastically cut back on the sulfur in the fuel. And as if that wasn’t enough, the new diesel exhaust filtration devices required oil formulations that were low in sulfated ash and phosphorous (low SAPS) oils.
Now those hurdles have been overcome and oil companies have gone back to focusing on developing products for better performance, not just cleaner air. The big trend emerging this year is low-viscosity synthetic oils. If you drop the viscosity you reduce fluid friction inside the engine resulting in a small, but not insignificant improvement in fuel economy and better cold weather performance. The trick is to formulate these thinner oils to provide the same or better wear protection than a thicker oil. The solution is a combination of synthetic base oils and a bit of formulation magic. The exact nature of the magic differs from company to company, but most of the oil companies have been testing their new oils this year and report not only some fuel advantages but better wear protection as well.
With the introduction of its Rotella Energized Protection engine oils, Shell basically overhauled its product portfolio and introduced what it calls “adaptive technology.”
According to Mark Reed, global brand manager, the oil’s “adaptive molecules” stay tightly wound in cold conditions and expand when the engine heats up in warm weather for wear protection in all conditions. Reed says tests show fuel savings up to 1.6 percent. That may seem like a small amount, but a 6 mpg truck going 120,000 miles a year on diesel that costs $2.50 a gallon will save approximately $800, Reed says.
As part of the product overhaul, Shell consolidated its portfolio into what it calls a “ladder of protection.” Shell Rimula, Pennzoil Long Life and Quaker State HDX products have been renamed and folded into the new portfolio. At the top of the ladder is the Shell Rotella T6 full synthetic 5W-40 oil for the most demanding environments and extended drains. That’s followed by the Rotella T5 synthetic blend in 10W-30 and 10W-40 viscosities. In non-synthetic oils, the Rotella T Triple Protection in 10W-30 and 14W-40 offers 38-percent lower wear than Rotella T CI-4 Plus and 22-percent less iron wear than Rotella T3 15W-40. For fleets looking for lower costs, the other end of the ladder is comprised of Rotella T3 in 15W-40 and 10W-30, and a straight grade Rotella T1 in 10, 30, 40 or 50 weight.
Liquid titanium is at the heart of ConocoPhillips new Heavy Duty Engine Oil and after four million miles of real world testing the company says it has shown considerable wear protection properties.
The liquid titanium isn’t a gimmick term; there is actual titanium in the formulations of the company’s Guardol ECT and Kendall Super-D XA oils. The titanium bonds to metal surfaces in the engine wear zones and adds an additional molecular shield of protection, says Steve Tarbox, director of product management. “It’s not an engine coating per se,” he says. “But when we do surface analysis on engine surfaces we will see titanium bonded to the metal surfaces specifically in contact zones such as cam lobes and crosshead wear surfaces.”
Along with the titanium additive, both oils are synthetic blend for increased oxidation stability and prolonged oil life. Analysis of oil samples of these products run in a variety of engines have shown less iron and very low levels of copper and lead, says Reginald Dias, manager commercial products. The oil analysis also showed the formulation maintained its viscosity and TBN, or total base number, throughout its use. In conventional oils viscosity and TBN tend to degrade over time.
Recently announced test results for Chevron’s Delo 400 LE 10W-30 oil, found fuel economy improvements from the lower viscosity formulation and as much wear protection as 15W-40 oils. Fuel economy was 1 percent better than the conventional 15W-40 oils and 0.5 percent better than 5W-40 synthetic lubricants, says the company.
According to Chevron, its ISOSYN technology uses a combination of highly refined base oils and advanced additives that offer the benefits of a synthetic based oil at a price comparable to mineral-based oil. “Viscosity used to play a more critical factor in engine durability, but advances in base oils and additives have redefined its importance,” says Nicole Fujishige, marketing commercial manager, Chevron Global Lubricants.
Aiming for extended service life, AMSOIL recently upgraded its CJ-4 Synthetic 5W-40 diesel oil and reports fuel economy improvements averaging 1.6 percent. The company says the oil can go up to three times the OEM recommended drain oil interval, not to exceed 50,000 miles, 600 hours or one year and may be extended further when monitored with an oil analysis program. The company has also upgraded its 15W-40 diesel engine oil to meet the CJ-4 specifications without sacrificing extended service life. EW