Hey Ya'll, Like others here I used to swear by Tap Magic. The original formula contained tri-chlorethane[sic?]. That stuff made beautiful, clean, smooth threads with no surface tearing. The difference in the threads, one with oil, another with Tap Magic, were clearly visable. Seems there was a chemical reaction when used on aluminum, chlorethane + aluminum + heat = fumes? I think this was the problem, but anyway the plant I worked at outlawed it. When the new formula came out, they removed the tri-chlorethane and added a different version for aluminum. I don't think it ever got back into the plant cause you had to buy two different cans. I think Rapid Tap became the replacement because you could use it on any metal. I'm pretty sure the tri-chlorethane was determined to be a cancer risk also, because it has been removed from everything. Well, we used to use it straight for cleaning high voltage cables and equipment. Yep, submerge a rag and your hands right in the bucket, wash your hands in it before going to lunch. Times change, rules change, I guess me and alot of other folks are screwed as far as cancer risk. Back to the drilling/cutting fluid, in my shop I use a sulpher based pipe threading oil for everything. I will take a lot of friction heat. I bought a gallon a long time ago and just refill my little squirt can, gets the job done and a gallon lasts a long time.