Through thick and thin

Max Kvidera | November 02, 2010

CHEVRON: A 10-grade will give you a quicker cold start than 15-grade.

Any oil grades you don’t recommend?

SHELL: You don’t want to use straight grade engine oils, such as straight 30 or straight 40. I still see them on retail shelves. They are old technology and don’t come close to meeting standards for durability or wear protection for modern engines, and they aren’t going to pump as well at low temperatures. n

What those numbers mean

The first number, such as the 15 in 15W40, identifies the cold starting viscosity, or resistance to flow or speed of flow. The lower the number, the lower the relative ambient temperature at which the oil could quickly flow and provide cold cranking power. Ratings are determined by the Society of Automotive Engineers.

The second number refers to the oil’s viscosity when hot under normal operating temperatures of 210 degrees Fahrenheit.

“W” commonly refers to winter, meaning the oil has been tested at cold temperatures.

“Diesel has the widest performance range with 5W40,” says Mark Betner of Citgo. “Its starting temperature range is down to minus 22 F (compared with 15-plus with 15W40) up to 122 degrees F (same as 15W40). That tells you a couple things: There’s a 37-degree cold cranking advantage (from minus 22 to plus 15) to a 5W40 and the same benefit on the high end.”

Oil for APUs

Increasing usage of auxiliary power units is reducing idling and fuel consumption. Yet if you don’t pour the proper oil, your APU may not work when you need it most. APU oil recommendations vary depending on the manufacturer, says Chevron’s Jim Gambill. For example, Comfort Master recommends a lighter viscosity, such as 5W40, 5W20 or 10W30. Kubota, he says, recommends a CD-class oil that won’t be allowed after 2010, or the same oil you’re using in your truck engine.

Dan Arcy of Shell Lubricants says you need to know your APU’s capabilities and where you will be running. If you have an APU that’s designed to heat the engine block, 15W40 oil will be sufficient year-round. If your APU doesn’t have that feature, he recommends using 5W-40 for better cold starts.

Mark Betner of Citgo Lubricants is of the same mind. He recalls a Western fleet that purchased 400 APUs. Some trucks traveled through Rocky Mountains and parked overnight in minus-30-degree temperatures. When they went to start the APUs, they wouldn’t turn over. He says, “15W40 was the problem all over again. That small 2-cylinder APU diesel had the same struggles as the big diesel does, only on a smaller scale.”

Longer interval, better viscosity

Every time owner-operator Earl Evans changes oil, he takes a sample for analysis. He does this to monitor metal deposits and wear on the 550-hp Caterpillar in his 2005 Kenworth W900L, which has 900,000 miles.

With the introduction of American Petroleum Institute standard CJ-4 oils four years ago, he has extended drain intervals to 25,000 miles from 12,000. Despite the longer periods between changes, Evans says the wear rates are the same as he saw at 12,000-mile intervals. “The viscosity is better at 25,000 miles than it was with the other oil at 12,000 miles,” he says. strives to maintain an open forum for reader opinions. Click here to read our comment policy.