If there is some sort of coating on the steel (i.e. e-coating), would that not change the overall thermal conductivity of the whole piece?
I have an oil pan and I want to add a vibration damper on it. To protect the vibration damper from thermal degradation, I need to add insulation between the vibration damper and the oil pan. To calculate the heat transfer rate I need the oil temperature, the pan surface temperature and the thermal conductivity constant of the pan (including the e-coat). If the oil temperature and the pan surface temperature is almost the same how can I calculate the insulation thickness required if dT (Toil - Tpan) goes to zero?