If you only had a clue …
Diagnosing trouble before it kills your engine can be simple if you put on your sleuth hat and use your oil analysis to identify the suspects, where they lurk, and the damage they can cause

By Paul Abelson
senior editor


Wouldn’t it be nice to have something that gave you a good idea of what’s going on inside your engine, how it’s running and how everything is holding up? By “everything,” I mean the cylinders, pistons, rings, camshaft, lifters and even injectors.

It would be even better if you got a hint as to how your oil is holding up, telling you whether it will continue to work for you and how long – something like a handy list of suspects and where they would most likely do their damage.

Believe it or not, there is such a thing.

It’s been around since World War II, but even today few owner-operators take advantage of it. Even fewer use it properly.

It’s oil analysis.

It can tell you volumes about what really is going on inside of your engine, giving you the information you need to head off minor problems before they become major ones.

First, select an accredited lab, one that meets industry standards for accuracy. It’s important to stick with just one lab, in just one location. All operate within reasonable margins of error because of equipment and procedural differences. If you stay with only one, you’ll get more consistent results. They will supply small plastic jars and shipping containers.

Make sure your samples are clean. You can take them from the waste stream when changing oil, but that may contain excessive sludge or solids, especially when you start draining. If you find out the oil is still good to go, you’ve dumped 10 or 11 gallons of oil prematurely.

Commit to an oil analysis program, and ask your lab for a pressure valve. It screws into an engine block oil gallery. Attach a 1/4-inch tube to a clean needle, the kind used for inflatable balls. Remove the dust cover and make sure the opening is clean. With the engine warm and running, insert the needle and let the oil flow into a jar. Stop when the jar is about three-quarters full. That’s the cleanest way to take a sample. Send it to your lab.

They’ll report back in a few days, either by e-mail, fax or snail mail, depending on what you sign up for. Abnormalities are generally reported immediately by phone or e-mail. Absent any problems, the report will say the oil is good for continued use.

Analysis measures wear metals in the oil. Iron (liners, camshafts, valve gear), chromium (rings), aluminum (pistons), lead, copper and tin (bearings) and others are reported. Analysis measures contaminants; silicon, sodium, boron and potassium. It measures additive components and the oil’s physical and chemical properties, such as viscosity, acid levels, acid-fighting alkalinity and detergency and soot. Analysis can flag any immediate problems.

Each report is just a snapshot, the results from a single moment in time. By running together a string of oil analysis reports, graphed for easier understanding, you can examine wear trends. That way, it becomes a prediction tool, identifying any wear that is occurring and when failures can be expected.

Most operators don’t take full advantage because it takes extra effort. Most just accept that with readings within limits, the oil is “good for continued use.” They look at reports and say, “My oil was OK, so my engine is still good.” But, if you don’t plot results, you miss a great deal of critical information if you plan to extend oil drain intervals or keep your truck a decade or more.

You need to plot your results either individually on separate spreadsheets or on graph paper, or on the same grid using different colors. Miles should be represented on graph paper along the horizontal axis and parts-per-million or percentage on the vertical axis.      

You will be able to see trends developing and will be better able to predict when levels will become critical. You can project oil life, then confirm your observations with oil analysis. Many labs and oil companies will even computerize your reports and do the plotting for you. Check suppliers to see who offers this service.

To start plotting, take samples halfway through every drain interval. Within two normal intervals (four samples), you’ll have trends established. You should know if it’s safe to extend oil drain. LL