Oil Analysis

[Brian Carlton]

Since I have switched to Rotella synthetic, I was curious to see how it was doing after going 8K miles. I purchased the analysis kit from the local Cat dealer. The results are interesting:

Cat does not provide absolute numbers in terms of percent or ppm. You only get their relative numbers which requires the opinion of the analyst to ascertain whether the level is high relative to other engines of a similar type.

So, all metals including copper, iron, chrome, lead, aluminum, silicon, and molybdenum are all very low. Iron is the highest but still quite low. The additives of calcium and zinc are still quite high.
The most interesting number is the soot. Cat has numbers from 0 to 200. Their comment is that a number of 140 is as high as you would normally want to see. Mine was 160. The overall evaluation was "abnormal" due to the elevated soot levels.

This vehicle always travels above 50 mph except when it is leaving its garage. So, the potential for excessive soot due to lugging at low speeds is non-existant.

So, my conclusion is that a good oil can retain its wear additives for many miles, but, soot is going to accumulate and there is little you can do about it. I am going back to 5K intervals. Everyone who runs synthetics over 10K should take note.