paint a test surface, be it scrap wood, or
scrap concrete in lieu of stucco, or whatever.
Let it dry well, then give it some accelerated aging by squirting it with the
hose a couple times a day. See if it goes
bad in a few months. If so, get rid of the
paint. If not, then flip that coin. ;-)
BTW, your test surface should be left out
in the sun.