Energy Prices:

Lab Methods

Back to Lab Methods

Sulfated Ash Content

  • Method ASTM D874
  • Repeatability 0.047(X0.85)
  • Reproducibility 0.189(X0.85)
  • Blending linear
  • Additive Correction No

The purpose of this test is to determine the sulfated ash from unused lubricating oils containing additives and from additive concentrates used in compounding. These additives usually contain one or more of the following metals: barium, calcium, magnesium, zinc, potassium, sodium, and tin. The elements sulfur, phosphorus, and chlorine can also be present in combined form. Be aware though this method is not designed for used lubricating oils only new production.

The test method is performed by weighing a ceramic crucible and adding sample to it. The crucible is then heated by a Bunsen burner until the sample lights on fire. Once it is burned down to where the flame goes out and there is no visible wetness the crucible is pulled and cooled. Sulfuric acid is then added to the crucible and placed on the hotplate to continue evaporating slowly until it is dry. The crucible is then moved to a 775°C oven for 30 minutes to continue removing all of the carbon so that only metals and sediment remain. Once the specified time is complete the crucible is pulled and cooled in a desiccator. When room temperature is reached the crucible is weighed to give a weight percent ash result. This process is repeated until two readings are in agreement.