Once upon a time glass setting tape was formulated so it expanded with kerosene (or even crankcase oil). You folks probably remember this. You installed your window, trimmed the tape, poured kerosene or motor oil on the rubber and overnight it would expand and lock in your window. I've been thinking about having made a rope seal which had a core of glass setting tape in the dead center so it would expand against both the crankshaft and the slot it sits in after it was introduced to oil. Makes perfect sense to me as the setting tape never went back to the original size after it expanded.
By interesting coincidence I had to replace a couple of pieces of glass recently and in my curiosity I bought setting tape from all the usual suspects. None of it expands. Not even a little bit and that includes the stuff that is rubber mixed with cork (a reasonable man would expect the cork to expand with oil). If any of you chemists or wannabe chemists know of a compound that does expand predictably when exposed to oil, please let me know. Please don't use Google and their AI answer. It will tell you nitrile rubber will be softened and expanded by oil, however I have tried both nitrile and epdm and it didn't work for me.
