Lubricant Compatibility Analysis

In the lubrication industry it is pretty common to have heard of or experienced a lubrication issue due to mixing of incompatible lubricants. Issues encountered include excessive foaming, formation of precipitates or deposits and loss of key performance characteristics such as water separability. Given the gravity of the impact on machine reliability that these issues can cause, there is a demand for testing that can help predict if mixing two lubricants might result in operational issues.

Although the lubricants may be deemed equivalent or comparable, that does not mean they are compatible. Contact TestOil about our Lubricant Compatibility Analysis if you are considering a change in lubricants.

The Process
ASTM D 7155 Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils is used as the guideline for compatibility testing. If test results show signs of minor incompatibility you must evaluate the potential impact. Do the mixtures show a decreased ability to resist oxidation? Will this result in a shortened lubricant life and therefore increased cost due to more frequent oil changes? If so, perhaps another replacement lubricant should be considered.If test result show signs of a major incompatibility, and the intention were to mix the lubricants via gradual system top-offs, a change of plans is warranted. If choosing a more compatible replacement lubricant is not an option, then the change out should be done using a complete oil change with a system flush to remove residual lubricant.
Reasons For Compatibility Analysis:
  • Equivalent or comparable lubricants are not the same as compatible lubricants
  • Use analysis to ensure that key physical and chemical performance properties of the lubricants will not be compromised by mixing the lubricants
  • Protect the life and performance of the lubricant and the equipment by avoiding lubricant incompatibility-related failure