The content of water in petroleum products plays an important role in predicting quality and performance of the product. If moisture is present, premature corrosion and wear, diminished lubrication, filter plugging, decreased effectiveness of additives, and bacterial growth may ensue. Dissolved (entrained) water, not detectable by the human eye, is measured by ASTM D6304, Coulometric Karl Fischer Determination. This test method is applicable to moisture concentrations as low as 10mg/kg.
ASTM D6751 Requirement: None. However, many distributors require 500ppm or less.