I worked for a FBO at Toledo airport a very long time ago and we discovered a 55 gallon drum of butyrate that was over ten years old, had never been opened! They couldn't find the paperwork on it and their records went back those ten years. We opened it and it was like the syrup you mentioned! Since we were recovering several Piper Colts we decided to try it, and it worked fine. Took a LOT of thinner, but Randy's right, the stuff will pass thro8gh metal over a period of time.