We currently have found a change of additive type in a popular singel grade diesel engine oil. The product has been around for centuries and has allways contained between 2000-4000 ppm Calsium (Ca) and around 200-400 ppm Magnesium (Mg) TBN is 11 (last voa was in 2000).

Today we have three different clients using the same oil type, but in 2004 something happend with their oa results. Our analysis (from only theese clients) showed <400 ppm Calsium (Ca) and 1000-2000 Magnseium (Mg). TBN value is around 11 (normal).

The manufactorer claims the Ca and Mg values are correct for this oil type, but they do not comment why/if it has changed.

Is it possible to have an engine oil without Ca ? Do you think the manufactorer has come up with a new additive pack that still contain the correct base properties without Ca.?

Need a little more info. You say you had a variance in three OA's from three particular clients using this oil. Do you have other clients using the same oil with a normal OA on Calcium and Magnesium? Based on historical data? In other words, other clients using the same oil have not had a change in their OA's with regard to Ca Mg content?