Recently, the Castrol® Field Engineering team has seen an increase in the use of Molybdenum (Moly) additives in engine oils. While Moly has many benefits in terms of engine oil performance, it has caused some confusion when interpreting Used Oil Analysis (UOA) results when these engine oils are in use.
The issue is that Moly can be both an additive and a wear metal. Moly as a wear metal in an engine sample would most likely come from piston rings. The current trend is that less and less Moly is used in piston rings, and when it is used, it generates very small numbers on a UOA report… usually <10 ppm. Generally, when there are considerable amounts of Moly in a UOA report, it is because it is a component of the engine oil’s additive package.
Some of our current engine oils and all of the new PC-11 engine oil formulations have a treat rate of ~50 ppm for Moly. Currently, this is causing undo alarms, or “false positives,” in the interpretation of UOA reports because the presence of Moly at 50 ppm can lead to B, C, or D severity codes. As explained above, this occurs because the result was interpreted as a wear metal when it was actually part of the additive chemistry.
For this reason and effective immediately, Castrol is no longer “flagging” Moly on Labcheck UOA reports. The amount of Moly in an oil sample will be shown on the report, but there will be no severity flagging associated with it. As with Moly, we will also not be flagging Phosphorous, Zinc, Calcium, Barium, Magnesium, Antimony, and Vanadium.
This should help to eliminate related false positives on reports that often result in undo questions or actions on the part of Labcheck users.