Big Blu Sub Zero is the most durable product of its kind for leak detecting under extreme conditions. Our temperature rating is -30°F to 200°F. Bubbles and foam will keep regenerating where other low temp products give out, freeze or become gelatinous. Sub Zero maintains a uniform viscosity over this temperature range remaining fluid on the coldest of days while remaining bulky and resistant to evaporation on hot discharge lines. Technicians who are familiar with the performance of The Original Big Blu solution will appreciate how we “kicked it up a few more notches”.