Oil Compatibility Testing ASTM D7155: Part 2: The Process

There are several considerations for determining the best compatibility test or slate of tests. Two of these considerations are:

1. Decide if you will test your current in-use fluid with the replacement fluid(s). If you have one lubricant system that’s transitioning to a new oil, it’s a good idea to test the used fluid with the replacement fluid.
2. Determine which mixtures you would like tested. ASTM D7155 calls for at least one mixture in the ratio of 50:50. Additional mixtures can be added if appropriate. If you are doing a complete change out, but some residual fluid may be present in the system and could mix with the new fluid then adding a 90% new oil to 10% used oil mixture is recommended. If the replacement fluid will be gradually added to the existing fluid, then three mixtures are recommended, either 90:10, 50:50, and 10:90 or 25:75, 50:50, and 75:25.

Eurofins TestOil’s Compatibility testing considerations are based on ASTM D7155 “Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils” as a guideline for compatibility testing. This protocol helps to determine whether mixing two fluids would negatively affect performance, stability, or system integrity. However, ASTM D7155 is not meant to establish the performance of a hydraulic fluid, only its compatibility when mixed with another fluid.

ASTM D 7155 categorizes these tests into four tiers; the first two tiers are required for accurate results; the 2nd two tiers are optional.  

Tier I: Visual Inspection: calls for heating the mixtures along with neat samples of the constituent oils for a period of time, then incubating at room temperature, with visual assessments of the mixtures for clarity and development of precipitates after both the heating and room temperature incubation. If no signs of incompatibility are observed during Tier I, then Tier II, Tier III and Tier IV testing should be considered.

Tier II: Interfacial Properties, tests include:

• Demulsibility ASTM D1401
• Foam ASTM D892
• MPC ASTM D7843
• Air Release ASTM D3427

Tier III: Physical and Chemical Properties, tests include:

• V40 ASTM D445
• V100 ASTM D445
• Viscosity Index ASTM D2270
• Color ASTM D1500
• Acid Number ASTM D974
• Additive Metals ASTM D5185
• Water Content ASTM D6304

Tier IV: Specific Performance Properties, tests include:

• RPVOT ASTM D2272
• Rust ASTM D665
• Copper Corrosion ASTM D130

Eurofins TestOil experts can help with determining the best compatibility tests for your situation. Read: Eurofins TestOil experts can help with determining the best compatibility tests for your situation. Read: Compatibility Testing ASTM D7155: Part 1: Overview.  Stay tuned for Compatibility Testing Part 3: Avoiding the Consequences of Incompatible Oils. 

For more information on partnering with Eurofins TestOil on oil analysis programs or training opportunities, fill out the form below; visit https://testoil.com/company/contact-us/; call 216-251-2510; or email sales@testoil.com.

About Eurofins TestOil

With more than 30 years of experience in the oil analysis industry, Eurofins TestOil focuses exclusively on assisting industrial facilities with reducing maintenance costs and avoiding unexpected downtime through oil and fuel analysis program implementation. As industry experts in diagnosing oil-related issues in equipment such as turbines, hydraulics, gearboxes, pumps, compressors and diesel generators, Eurofins TestOil provides customers with same-day turnaround on routine oil analysis testing.  For more information on partnering with Eurofins TestOil on oil analysis programs or training opportunities visit https://testoil.com. Contact: Al Yates 216-251-2510; sales@testoil.com. 

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