Thermal conductivity values for all four Skydrol grades are published in Eastman's Skydrol product comparison brochure (Publication EASAF7870), tested per ASTM D2717 at 100 °F, 200 °F, and 300 °F. Unlike the specific heat data on the companion page, thermal conductivity is reported at all three temperatures for every grade, so the calculator here linearly interpolates between three well-populated anchor points for each grade. No extrapolation is performed: inputs outside 100–300 °F return "Out of Range."

Thermal conductivity decreases with increasing temperature for all four grades, typical of liquid hydraulic fluids. Skydrol PE-5 has the highest thermal conductivity of the four grades at a given temperature; Skydrol 5 has the lowest.