Trying to open an old wallet.dat (from ~2013) I found my old wallet.dat file taken from the bitcoin core wallet I used when mining around 2013, nothing serious tho, just fiddling around. Never been too much into the subject, and now I'm totally out of the loop.

Will explain what I did so far:

I downloaded the latest bitcoin core, opened it and after a few seconds closed it properly, replaced the default wallet.dat file (with a size of 1416kb) with a copy of my old one (only 88kb) and opened the program again to let it download blockchain, then noticed that as soon as the program opened, the wallet.dat (my old one) file size changed to 688kb, waited for the  whole blockchain to download and noticed the balance it's still 0, the send/receive/transactions screens are also blank, as a vanilla wallet.

Maybe my old wallet file is somewhat an old format and get's erased and treated like a new one?



I put back the default wallet created by the program and from inside the program opened my old wallet file, a small window with a progress bar appeared saying "opening wallet filename", but it keeps loading forever. Also the file size changed again from 88kb to 688kb.

Any clue of what is happening?

I wan't to transfer whatever is there to some online wallet like coinbase.
You could try checking balance from blockchain, just click on receive and copy the address and search in blockchain.com, youll see you'll how much you got there.