Lab Report: What story will your oil tell?

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Any shift in wear metals in your oil will help to tell a story.

Regular oil sampling provides insights
into the condition of your oil and engine

Human beings aren’t much different from the trucks they drive. Like humans, trucks can have stuff going on inside that could prove detrimental to longevity. Since we can’t open a door and peer inside for a look, we rely on blood tests, blood pressure checks, cholesterol, and blood sugar tests, to name a few. Oil sampling and analysis provides a similar level of insight into the internal condition of engines.

Oil analysis provides insight on several levels. You can verify the condition of the oil at certain mileage intervals, which is useful when planning extended oil drain intervals, and you can also determine wear rates of certain engine components by looking at the metal content in the oil sample.

“Every individual engine will have its own wear-metal signature,” says Andre St. Jean, director of analytic services with Montreal-based Total Canada, which produces Quartz and Rubia engine oils and lubricants. “Different brands and models of engine will be different, too, because they are made of different materials. What is considered normal wear will also vary from engine to engine. It’s important to watch for the wear, but the wear trends are equally important.”

All truck engines will wear as they work, but you need to establish from the start what are normal wear rates. That’s why St. Jean suggests sampling when the engine is new, and then on regular intervals as it ages.

“You’ll want to pull a few samples early to establish a baseline,” he says. “After that, you may not need to sample each time you drain the oil. You can change the sampling intervals to rationalize the cost, as long as you’re not letting it go too long between samples.”

The metal content of the sample can reveal exactly where it comes from, such as bearings, heavy parts like the crankshaft, and even pistons, rings, and liners. Among the advantages to knowing which parts are wearing normally — and which exhibit accelerated wear — is protection in a warranty claim, and even clues as to when it might be time to sell the truck.

“Some fleets will try to run a truck out as long as possible before getting into big repairs,” says Gloria Gonzalez, general manager of WearCheck in Mississauga, Ontario. “Fleets want to monitor the life of their engines, so they will know when it time to sell.”

Analysis can also reveal traces of contaminant in the oil, such as coolant or fuel. If that material is making it into your oil, it could also be traveling downstream into your aftertreatment system. Catching an oil or coolant leak early can reduce the possibility of a very expensive Diesel Particulate Filter repair or replacement.

Oil analysis is (or should be) also a critical part of any extended oil drain interval program. Gonzalez says it’s possible to double the typical oil change interval using some of today’s very capable synthetic oils, but you can’t go forward with such a program on guesswork.

The oil itself doesn’t actually break down over time, but certain necessary additives may be depleted. That can reduce its cleaning properties or its ability to neutralize contaminants such as combustion by-products and acidic materials.

“With the oil itself, the most important number is the TBN number,” says Gonzalez. “That will go down over time, and you don’t want to let it drop past the point where you’re putting the engine at risk.”

The Total Base Number – usually referred to as TBN — is a measure of alkaline additives in the oil, which protect against corrosive combustion by-products like soot.

Soot loading of the oil is another important measurement obtained from regular sampling. Soot is suspended in the oil, but if you push the drain interval too far, there could be so much soot in there that the oil becomes abrasive.

How much can you expect to pay for such a service? As with any Return on Investment calculation, it’s not what you pay that matters, but how much you save. Jack Fasoli, heavy duty national key account manager at Total Canada, says even when you include the cost of the oil analysis in an extended interval program, the returns are very clear.

“Even if you’re using a superior quality oil, like a synthetic blend, by extending your drain you’re saving money,” he says. “And you have peace of mind. You can’t afford a breakdown. It’s a bit harder to calculate, but there is value in knowing your equipment is less likely to let you down.”

Gonzalez agrees that the value is in the protection oil analysis offers.

“Even if you’re paying between $25 and $40 per sample, it’s going to help you keep that truck on the road,” she says. “How do you calculate the cost of a breakdown, with repairs, towing costs, loss of customer confidence … that can be very expensive.”

Oil analysis is a predictable cost, and it can be built into the maintenance budget. While it won’t prevent every possible engine-related problem, it does offer an early warning mechanism that maintenance staff can respond to, hopefully before it’s too late.

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Jim Park was a CDL driver and owner-operator from 1978 until 1998, when he began his second career as a trucking journalist. During that career transition, he hosted an overnight radio show on a Hamilton, Ontario radio station and later went on to anchor the trucking news in SiriusXM's Road Dog Trucking channel. Jim is a regular contributor to Today's Trucking and, and produces Focus On and On the Spot test drive videos.

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