I know that logically any older appliance is an “energy hog”, but I have to agree with Al on not noticing a difference.
I own my grandparents old place in Nebraska and with it came the 1947 Kelvinator refrigerator that they purchased new when they got electricity to the house. It had been moved to a “back-up” fridge in the utility room in the late 60’s and more recently was only used for drinks and such the 4 or so weeks a year I am there. It has run faithfully from that point until I regretfully unplugged it a couple years ago and replaced it with a newer model thinking it was the main draw on my monthly ~$30 electric bill. Well, the bill has gone up, likely the rate, but I have not dug into it. We are on the 3rd “newer”, primary refrigerator in the kitchen… I think the Kelvinator will find its way back into use next trip there!
Let us know how you come out,