I use paraffin, but I use it sparingly.
I don't believe it attacks the o-rings (though I have no hard evidence to prove this).
I do worry that soaking in paraffin might cause some to pass the o-rings and thus dilute the grease inside.
But neither of these are verified.
I have recently bought one of these chain cleaning brushes .. but its early days to report on its effectiveness as I've only used it once or twice so far.
https://www.ebay.co.uk/itm/TIROX-360...8AAOSwaB5XpHj4