Westfield_XI said:
I too have several bottles of Sta Bil that are at least 10 years old and would like to know if they are any good. I found them while cleaning out boxes of old motorcycle stuff a few months ago.
did a bit of research and found a slightly ambivalent response.
Magic Plus says: "MAGIC PLUS FUEL ADDITIVE has a very long shelf life. However, the recommended product shelf life of MAGIC PLUS FUEL ADDITIVE is three years from the date of manufacture, as indicated in the packaging. However, our test results have shown that the additive works even beyond this period. However, care should be taken to store the package under normal room temperature and a dry place, away from sources of heat."
STP says: "The storage life of STP® products is guaranteed for a minimum of two years. However, although our testing guarantees a minimum of two years' shelf life, our experience has indicated that if our products are stored properly, they can remain stable and retain their effectiveness for an indefinite period of time."
seems like it goes on forever(ish) but the companies don't want to say so.