Most of the latest premium oils meet the CJ-4 standard for 2007 engines, which requires reduced consumption – one quality of a superior oil. Less oil burned also means, on 2007 engines, less frequent cleaning of the diesel particulate filter.
Even with its higher cost, premium oil has the potential to save money with fewer engine repairs, longer engine life and extended oil changes that save far more than simply the cost of the oil. But other savings can accrue as well. If the premium oil has a lower viscosity in frigid temperatures, it can protect the engine better at cold start, reduce idling, and save on battery and starter repairs. Some fully synthetic oils also improve fuel economy.
engine repairs, longer engine life and extended oil changes that save far more than simply the cost of the oil. But other savings can accrue as well. If the premium oil has a lower viscosity in frigid temperatures, it can protect the engine better at cold start, reduce idling, and save on battery and starter repairs. Some fully synthetic oils also improve fuel economy.
“Oil companies offer two or three performance levels,” says Mark Betner, Citgo Petroleum’s heavy-duty product manager. “Better oils last longer, neutralize more acid, and handle more soot. Why not take advantage of that?”
Many owner-operators change oil conservatively – at about 15,000 miles. But this is not your father’s oil, especially if you’re using the higher grade oils. Depending on how you operate, a change interval once considered appropriate might not be right today. Being willing to extend your change interval may be required to make the most expensive oils pay for their premium.
WHAT’S SO DIFFERENT?
Engine oil isn’t a commodity. There are significant differences among products. A refiner willing to put extra dollars into ultra-sophisticated refining or exotic additives can produce an oil that will resist breakdown longer, pump better at cold temperatures, and perhaps maintain acid protection with less ash. This last benefit allows use of superior CJ-4 oil – the new category for 2007 engines – even with higher-sulfur fuels.
Oils in the past were merely distilled out of crude petroleum, using heat and pressure to isolate those fractions of the barrel that had the right lubricity and viscosity, compared to the thicker and thinner stuff. These oils isolated by heat and pressure are called Group 1 base stocks. But as time went by, pioneers such as Conoco-Phillips developed a more sophisticated refining technique, which Reginald Dias, director of commercial products at ConocoPhillips, says is termed “hydro-cracking.” This allows impurities to be removed through chemical reactions, not just through heat and pressure, resulting in Group 2 base stocks.
“All modern heavy-duty engine mineral oils are based on this technology,” says Steve Goodier, technology director at BP North America, which makes Castrol oils. The result is oil that holds up better under the high heat and oxygen present in the crankcase, a quality called “oxygen stability.” Since this means a reduction in the portion of the oil that is susceptible to oxidation, it actually reduces the acids in the crankcase. This is exactly what ExxonMobil was able to do with its better CJ-4 oils in order to guarantee acid protection that is equal to that of its CI-4 oils while also meeting the CJ-4 requirement for lower ash, says ExxonMobil’s Doug Pond, a products adviser. “We have one of the highest TBN levels at 10.5, but we want to stress TBN retention.” Pond reports that Mobil Delvac 1300 Super’s CJ-4 actually retains TBN longer than the company’s CI-4 because of its more highly refined base stock.
Fully synthetic oils are derived through a chemical process, taking components of the crude oil apart chemically and reassembling them in a completely different form. “Synthetics have better oxidation and thermal stability, film strength and better low-temperature properties,” Dias says.
As for viscosity, customers often place too much importance on it and misunderstand its function. “What’s important is dynamic viscosity,” argues Goodier, who points to his company’s fully synthetic Castrol Elixion 5W-30. “Traditional viscosity determines how long oil takes to pour through an orifice. Elixion passes the High Temperature High Shear test that simulates viscosity in a journal bearing.”
This lower viscosity can have big cost advantages, including fuel economy and parts protection on cold mornings.
WHERE DO YOU SAVE?
Even if you change your oil at a standard, conservative interval, you are likely to save by using premium oils. Better oil combats wear more effectively, and that means fewer repairs as an engine ages and a longer life till overhaul. An engine that effectively runs 1 million miles instead of 800,000 reduces the cost per mile of that overhaul 20 percent.