When my grandfather died, we found piles of film stashed all throughout the house. Ten rolls in a dresser drawer, a box of fourty or so in a closet corner...etc. There were over 150 rolls of film in all. Almost all of it Tri-X. Dates were 1973 - 1996. None of this film ever saw the inside of the fridge and his house in rural Wisconsin wasn't even air conditioned. All of the film landed in my hands. I shot it all and was very pleased with it. I laugh about people who insist that film will go bad if not kept in the freezer.
What would I do with a boat load of film? USE IT! and be happy.
What kinds of issues do you have with expired film? Is the exposure just a bit wonky, or do the photos just not turn out at all? I would hate to lose a whole roll just because it was expired or mistreated.
Base fog increases, which decreases contrast, for better or worse. Usually prints will also be more grainy, also for better or worse.
Trying to understand just how much films will change is difficult at best. Environment matters, particularly temperature.
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh
I would test it out to see what the new speed is by conducting controlled exposure like I did with this Kodak Ektar 125 which shows expired 4/1992. Based on this I figured that it is best set at ISO32 so I have latitude on either side for best flexibility.
the great thing about using expired photo products is
the randomness, and crap shoot that it might be.
the film may work as it did the moment it was produced
or it may do weird stuff. personally i don't mind the weird-stuff
i kind of look forward to it, otherwise photography becomes
just a boring exercise of technical perfectness, perfect contrast
perfect this and that ...
as a antidote, put a little wabi-sabi in your camera ...