Soot is a natural enemy of diesel crankcase oil, resulting from incomplete combustion of the fuel during service. Its presence at high levels can threaten or impair the reliable operation of the engine.

At very high levels, suspended soot can become abrasive leading to accelerated wear in boundary contact zones such as cam/cam-follower pairs. To help mitigate the risk, an additive called the dispersant is used to control the size-growth of soot particles that leads to loss of suspension. When so much soot is experienced that the dispersancy fails, the oil can throw sticky carbon sludge that can obliterate oilways and plug filters. And, as soot load builds, the oil viscosity increases.

Because of the growing interest among fleet owners to extend drain intervals by routine monitoring of crankcase oils, there is a marked demand for information on soot loading and dispersancy as a key oil drain indicator. This has lead to the recent introduction of a new field-level instrument called the Soot Meter employing infrared analysis.

The unit is especially easy to use because samples can be applied directly to the top-mounted ATR measuring cell from the end of a dip-stick or simple eye-dropper. Analysis can be done in less than 30 seconds with results shown as percent soot. Cleaning is done by wiping the scratch-resistant cubic zirconia cell with a cloth or paper towel.

The instrument is truly portable, weighing less than five pounds and is roughly the size of a six-inch cube. The 12-volt power supply enables it to be used just about anywhere, from along side the engine to commercial oil analysis laboratories. Recently, the Soot Meter has been tested by the research laboratories of both Mobil Oil and Texaco. At Texaco (Equilon), the unit was compared to the lab's near-infrared spectrometer. The results illustrate an impressive 99% correlation (R2). The Soot Meter is a recommended instrument by Texaco. Click here to see the results of the Texaco study.

In another test program, at Mobil's Paulsboro Technical Center, the performance of the Soot Meter as compared to FTIR spectrometric and thermogravimetric analysis (TGA) was evaluated. The TGA method is widely regarded as the most precise for soot load measurements but, because it is time consuming, it is not practical for routine monitoring of used oils. The results of the Paulsboro study are equally impressive. Click here to see the results of the Mobil study.

For more information on the soot meter contact Wilks Enterprise, Inc. at 203-855-9136.