A broken connecting rod poking through the side of the block is a sure sign that something's not quite right inside an engine. So are unusual sounds from within, lower than normal oil pressure, and smoke or strange smells, to name a few. While perfectly valid indicators by themselves, they all have one thing in common: It's too late. Much like relying on so-called idiot lights, by the time the alarm goes off, some damage is already done. Keeping an eye on good gauges is a big step in the right direction, but those still only tell what's going on now, not what's about to happen-and certainly not why.
Having saved an expensive motor with oil analysis, we are firm believers in this early warning system. It may sound high-zoot, expensive, and complicated, but using oil analysis is really quite simple and affordable. You basically grab a bit of the old lube from the engine-or any component that's lubricated by oil that you wish to sample-and mail it to a laboratory. About two weeks later you get a report back that shows what levels of contaminants and evil things were in there. It's a lot like taking a blood test at the doctor's office, except that you'd normally take the oil sample when changing the oil. If you need to replace your blood, you have problems well beyond the scope of this story.
Should the doctor find something unusual with your blood test results you'd get a phone call right away, and that's how a good oil analysis lab operates. Both are aimed at catching a problem early and thereby minimizing the damage, hopefully avoiding catastrophic failure altogether.
What Are We Looking For?
Oil analysis isn't meant for finding nuts and bolts in the oil pan-that's what magnets are for. Rather, through physical tests and spectrochemical analysis, the oil sample is searched for over two dozen contaminants, from metals to water. The two services we used for this story, Shell Care and Staveley Services Fluid Analysis, both have a listing of the possible sources for these contaminants on the back of the lab reports. Boron, for example, is used in most antifreezes, but in some cases also as a motor oil additive. That's one reason the laboratory must know what oil and grade was used in what engine, and for how long, in order to make a more meaningful report.
We're not particularly concerned with the well being of our tractor's tired L-head Four (or it wouldn't get the used oil from our other vehicles) since it's not an expensive or hard-to-fix motor. Oil analysis makes sense when there's more money at stake, which includes most any diesel engine. Even our lowly Blazer's 6.2 Detroit gets a sample taken at each oil change. At about $10 a year, that is a very inexpensive early warning system.
When asked what would be the last thing you'd want to see on the analysis report, both Staveley's Stan Light and Shell Care's Gene Wagenseller agreed that coolant in the oil is the worst for the motor. Coolant attacks tri-metal bearings aggressively; a chemical reaction thickens the oil and the bearings go out quickly. Since the water in the coolant mixture normally boils off, there's often no real clue to be had by checking the dipstick-unless the oil level is suddenly higher and the coolant level is down. It's when finding coolant in the oil that you get a phone call, e-mail, or fax from the lab, to let you know now. That's what saved one of our motors from becoming expensive junk. Instead we had a usable core.
Both also feel that dirt is the second worst. "It's just plain abrasive," says Wagenseller, and can enter the engine through loose connections or bad filters. As four-wheelers, we should probably all take note on that one. After studying our reports more carefully, we ordered up a True Flow filter for our pickup to replace the paper stocker, having seen a very convincing demonstration at a trade show.
Third on the list is raw fuel. Gasoline in particular isn't a good lubricant, and diesel isn't exactly great, either. Wagenseller suggests using heavy stationery to test for fuel dilution. Pour some oil on the paper and if it runs out from the center quickly, it's likely diluted. Obviously, an analysis is a far more precise testing method. We've all seen the resulting black smoke from poorly adjusted carburetors on the trail, and surely some gas made it into the crankcase, too, if the fuel mixture was that rich.
Each of the contaminants listed on the report will say something about the state of the sampled component, and by comparing the results to the listed sources, you can get a darn good idea of what's going on in there.