I have some generic C41 film that expired in 1995. These were stored in unknown condition and probably very VERY badly. They are supposed to be ISO 800. Brand is "Walgreen" (a large drug store chain in US) but it means absolutely nothing. Knowing full well the answer might be "well, it all depends...", I have to ask because I have no idea. What EI should I rate these? Shoot at 800 or rate it half, say 400? I do not expect perfect results. I'm actually looking forward to seeing wildly shifted colors. What I'd rather not get is awfully underexposed negs. Are there any collective wisdom on these unknown film? By the way, I have no ability to do my own processing for color so I'll be taking to a mini-lab place. Anything other than standard C41 isn't an option. Thank you.