I am doing a large project for myself and some friends, lots of long prints with PLA, it is a good chance for me to use up many spools of old pla that literately has been sitting around for 2-4 years and have been either sealed or stored in sealed containers with descant. I've been using a mix of brands with no issues, with some slight temperature differences as needed, and even used some new inalnd pla to round it out as i didn't quite have enough of the old stock to be able to complete everything.
all was going well until i started using one spool of orange PLA (distributed my makerbot circa 2012-13ish - yea yea i know takerbot .. but it was free) about 12 hours into a print, the extruder jammed, (stripped filament not clogged nozzle), ok bummer, but the plastic had started to literately run like water out of the nozzle. .. like it is suddenly got highly it over temp for the plastic.
my first reaction was, 'crap, temperate sensor went'... but...switching to other PLA, its fine. The temperature for the v3b was set to 212.
Subsequent test had the same issue with this spool, and ended up backing the temperature way down to do some test prints with the orange pla... its as if the composition of the plastic changed mid spool.
checking the filament itself, it is flexible like ABS, both in filament and printed form, not brittle like i am used to pla being. temps need to print are very low as well as it is hard to print with it because the gear gouges out/strips the filament so easy, easier then abs.
here is another weird fact, its soluble with acetone.
i am guessing this is not PLA or ABS, perhaps it was a manufacturing issue where they changed plastics mid spool???...anyone have a clue what kin of plastic it might really be other then just bad

i'm currently printing with some 2.5+ year old makergear natural pla at my original temps and it is printing just fine.