The density data from 5 °C to 70 °C (41 °F to 158 °F) was measured by NIST using a vibrating-tube densimeter (Anton-Paar DMA 5000) at ambient pressure (~83 kPa). Each tabulated value is the average of three to six replicate measurement scans. The absolute expanded uncertainty is 1.65–1.66 kg·m⁻³ (relative: 0.12–0.18 %).

The range is extended to −40 °C (−40 °F) and 200 °C (392 °F) using a linear extrapolation with slope (−3.77 kg·m⁻³·°C⁻¹) matched to the NIST measurements. Maximum deviation from the NIST measured points within the 5–70 °C range is 0.09 kg·m⁻³, well within the measurement uncertainty. The high-temperature end is capped near MIL-PRF-23699's own 204 °C corrosion/oxidation stability test temperature; no published density measurements exist above the NIST 5–70 °C range, so all extended-range values — including this capped region — should be treated as rough estimates only.

MIL-PRF-23699 is a fully qualified synthetic turbine engine oil based on polyol esters (POE). Its density falls between that of pure POE5 and POE7, and is very similar to pure POE7. Density decreases approximately linearly with temperature across the full range.