One kg of steam is equivalent to 27 Kg of thermic fluid to deliver the same heat content. For heating applications less than 200degc, steam is preferable to thermic fluid as heating media.
Of all heating media, steam is one with the highest energy content. To go by numbers, 1 kg of steam has around 540 Kcal of heat content while 1 kg of thermic fluid (High temperature oils) has around 20 Kcal of heat content.
This implies that for every one kg of steam you need 27 Kg of thermic fluid to deliver the same heat content. Therefore the quantity of thermic fluid to attain a specific temperature would be 27 times more as against steam.
For processes requiring very high temperatures (in the range of 250degC), steam at high pressure is required. Even though steam is most efficient energy carrier, the cost involved in the manufacture of the equipment necessary to handle such high pressures makes thermic fluid commercially viable.