Down to a science

| June 07, 2008

A precise report that reveals exactly how much of a certain metal is in your oil is nearly useless unless the lab knows exactly what model engine you have. An amount of a certain metal that may be perfectly normal in one engine could be a sign of serious trouble in another.

Oil analysis ensures you’re changing your oil at the right interval and warns you of developing trouble. Owner-operator Charlie Flexter, who hauls grain in often heavy central Illinois traffic, says oil analysis found that his conservative 15,000-mile oil change interval was actually too long for his Cummins engine, and he went to 12,000-mile intervals.

On the other hand, when using the latest, high-quality CJ-4 oils and running relatively new engines, truckers who drive over-the-road and don’t idle much can often safely use analysis to extend changes, in some cases to 30,000 miles or more. Why throw good oil away?

Experts from several refiners made it clear to us that oil analysis is a science. Unless you know a little about that science and how to make it work for you, you won’t be getting the full benefit of oil analysis.

Filling out the sample form
Something as simple as correctly filling out a form can have a big impact, says Lilo Hurtado, CVL applications engineer at ExxonMobil.

“People do not always take the time to fill out the form that comes with the sample properly,” Hurtado says. “It makes a huge difference.”

Shawn Ewing of ConocoPhillips Lubricants says, “Timely and accurate information is first and foremost when it comes to a good analysis report. When better information is provided to a lab, better results will be returned.”

BP Castrol Technology Manager Steve Goodier says, “Without the proper information on the form, the result can be absolutely meaningless.” He says that BP Castrol’s service, Lab Check, uses an online system that allows the fleet to create a form for each vehicle so that all the information that doesn’t change only has to be filled in once, which helps avoid errors.

Hurtado recommends you make sure to put all these items on the form and check that they are correct:

  1. Engine make and model number, as well as all other equipment information.

  2. The date when the sample was taken.
  3. Oil name and refinery brand.
  4. The viscosity of the oil, for example 15W-40 or 10W-30.
  5. The miles (or hours for off-road trucks) since the last oil change.
  6. The miles on the engine since the last overhaul.

Walt Silveira, Shell Lubricants’ North American technical manager, recommends including the amount of makeup oil added since the last change. Keep a record of how much oil you add and put the total on the analysis form.

Silveira also says an independent lab should get a sample of the oil right out of the bottle. This is even better than having them read off the oil data sheets, because the sheets show only typical values of items like additives, rather than the actual values in the oil you used.

It’s also vitally important to make sure the sample is pure. Goodier says Lab Check provides new sample bottles for each sample. Merely cleaning out the old bottle with diesel fuel may not remove every trace of material from an earlier sample.

The whys
Including the date and other equipment information along with the miles since the last change will help keep samples properly identified – thus, they won’t be confused with one another. This would help, say, if you had three trucks with C-15 engines and you always changed their oil at as close to 25,000 miles as possible.

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