That's helpful, thanks.
A couple of things occur to me.
One is that some cats are just plain food-fixated.
However, I will qualify that by saying when a cat has been living rough for some time, they can exhibit very food motivated behavior. Usually, once they've been in a new home for a time, they become reassured that food is going to turn up regularly, and they modulate their feeding behavior again, so they become less fixated on food.
All three of my own current cats were strays, and were without food for some time. Moray has never been too fussed about food, but the two girls were very aggressive over food when we first adopted them, and would scrap with each other at mealtimes unless fed at opposite ends of the room.
Six months later, they're both now much more relaxed over meals and the whole "fight for food" thing has disappeared.
The second is we can often misinterpret a cat's cries for attention as requests for food. We then feed instead of doing what the cat originally wanted (maybe because we didn't get the cat-speak and correctly interpret what our cat really wants), and so begin to perpetuate a cycle of behavior which doesn't ultimately satisfy the cat's needs, although it rewards the immediate request, if you see what I mean?
I think this has probably already occurred to you, as you recognize the issue might be more complicated than it initially appears.
My gut instinct is that what Oscar wants, is more time with you. You're out at work all day, so he has to make the most of his time with you when you get home.
Different cats require different levels of interaction - some like it short and sweet, some like it fast and furious, others enjoy long, lingering cuddle time (which is why we're so attractive when we're lying in bed - cats know we'll be likely to be there for a little while, we're less intimidating lying down and we often welcome time with our cats before dropping off to sleep).
Every cat we've had has enjoyed spending time with us in the bedroom at night, sleeping on the bed, sometimes waking us up to play or have cuddles in the night. As I'm a bit of an insomniac (as are many of Purrs members - maybe it's the cats?
) it doesn't bother me, but everyone is different. Some need more uninterrupted sleep than others.
I would maybe try the "show me?" routine with Oscar. When he cries, ask him to show you what he wants. If you've fed him, and he still cries, ask him to show you what he wants - a session with a play toy? A gentle stroke or cuddle time? To use a scratching post with you watching him? Playing with a rolled up piece of paper or a ping pong ball? You get the idea.
I think the change of food would be good too, and you could keep one or two treats such as "dreamies" for food rewards, maybe at playtimes. If you can try and make those as regular as your day to day routine will allow for, it'll help settle Oscar into anticipating his "me time" more quickly.
I don't see it as a case of "giving in" to Oscar, but rather trying to work out what it could be other than food, that he wants you to share with him. Sometimes, he may even just want you to pay attention to him, and walk round the house with him, and then go back to doing what you were doing. the main thing in Oscar's mind will be, he got your attention, he got to spend time with you, and you did something together. Doesn't have to make sense to us, as long as it makes sense to him.
A long time ago, one of my cats would love to spend time with me when I was in the bath, and he'd perch on the end near the taps and just beam at me (he was a very smiley cat!). Sometimes he'd tap the bubbles with his paw, sometimes he'd just have a leisurely wash himself. he didn't really mind, it was just the "two of us" time that he wanted.
Does that make sense?