J. Thomas
We have been using it (Duratherm) in our oil jacketed extruder as a heat transfer fluid for over a year now with no problems. We generally run between 180° and 190°C and often run for months between shut-downs. The oil still looks as clear as it did when we first put it into use. I am very pleased with the product and would buy it again if it ever wears out, but that might be a while!