Pete,
Barium is a metallic base for additives (dispersant/detergent additives as Doug stated) that are often added to AW oils. You should not loose any sleep over the fact that Ba has been detected in your oil. I also believe that you had it in your oil all along. Previous lab reports may show “zero” Ba, but that might have not been correct. The reason for my statement is the (wrong) practice of many labs to report “zero” for any finding that is below detection limit of their instrument or method they are using. For example, if the measured concentration was 28 ppm, and the detection limit was 30 ppm, the lab reports “zero” instead of >30 ppm. I have seen too many times reported water concentration as “zero”, which we all know is not realistic and most likely not true. Result reported, for example, as >0.5% would be much more accurate and helpful to the customers than reporting it as “zero”. Look at your reports and see if the lab reported concentration for all other elements as “less than” what ever the detection limit is, or they reported “zero”.
However, you should not loose any sleep over the fact that Ba has been detected in your oil. Ba is not present in an elemental form, and as such cause wear or any other problem.
