Measurement and testing
Developed by the flow properties subcommittee (D02.07) under ASTM's petroleum products, liquid fuels and lubricants committee (D02), the method is designed as a modern, automated alternative to the long-standing manual referee method, D2386.
The change that matters to lab managers is the removal of operator judgement from the result.
D2386 is a manual method that relies on a technician visually assessing the point at which wax crystals form as a fuel sample cools – a determination that, by its nature, carries an element of subjective interpretation.
D8615 replaces that visual assessment with an automated optical measurement, which ASTM says minimises operator intervention and removes the subjective judgement inherent in reading crystal formation by eye.
Hibiki Ikeda, General Manager for sales and marketing at Tanaka Scientific Limited and a member of the ASTM subcommittee that developed the method, said the new approach offers a modern alternative to D2386 specifically because it removes the need for visual assessment, improving objectivity and repeatability of results.
That repeatability matters most in referee testing – disputes over whether a fuel batch meets its freezing-point specification, where a manual method's built-in variability can itself become a point of contention between supplier and buyer.
The method's reported precision figures support the case for automation: reproducibility (R) of 1.30°C and repeatability (r) of 0.95°C, with results reported in 0.1°C increments across a measurement range of –80°C to +20°C.
The standard's own reporting range for valid precision claims runs from –71.2°C to –36.5°C, reflecting the temperatures relevant to aviation turbine fuel specifications.
D8615 is explicitly designed to support testing of sustainable aviation fuels (SAF) as well as conventional jet fuel, which extends its relevance as SAF blending becomes more routine across the supply chain – fuel manufacturers, regulators, contract laboratories and other supply-chain parties can all use the method to verify freezing-point compliance under a single, automated procedure rather than relying on the manual referee test with its operator-dependent variability.
For labs weighing adoption, the practical question is less about analytical validity – the standard is approved and precision figures are published – and more about instrumentation and timeline.
Automated coaxial optical fibre measurement requires purpose-built instrumentation distinct from the equipment used for manual D2386 testing, meaning adoption is tied to capital equipment cycles rather than a simple procedural change.
Labs currently running D2386 as a referee method should expect a transition period in which both methods coexist, particularly while cross-method correlation data accumulates and buyer/seller contracts continue to reference the older method by name.
There is a wider point here for anyone tracking test-method modernisation across ASTM D02 more broadly.
D8615 is not the first attempt at automating freezing-point measurement – D5901 and D5972 already offer automated optical and phase-transition alternatives to D2386 – but the coaxial optical fibre approach is presented as offering better precision than earlier automated options, with the reproducibility figures cited above representing a meaningful improvement over the variability historically associated with manual referee testing.
For contract labs serving multiple clients across the aviation fuel supply chain, the direction of travel across the committee is consistently toward methods that remove operator-dependent steps, and D8615 fits that pattern rather than representing an isolated change specific to jet fuel.
PIN 27.4 Aug/Sept 2026
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