Will a regular kitchen fridge survive an unheated garage winter?

Your read on the winter issue is right, and at -10 it's not a worst case thing, it's a guaranteed thing. I ran a regular fridge in an unheated garage up near the Cities for a few years and learned this the hard way. Went out in January and the stuff in the freezer section had thawed and refrozen into a solid block. Here's what happens: the thermostat that controls the compressor only reads the fridge compartment. When the garage is colder than the fridge setting, that compartment never warms up, so the compressor never kicks on. But the freezer depends on that same compressor, so it just drifts up to whatever the garage temp is. everythign in it soft-thaws over a day or two and you might not notice for a week. The fix is a heater kit. It's a little warming element that goes near the fridge compartment's thermostat and tricks it into thinking the room is warm, so the compressor cycles normally and keeps the freezer acutally frozen. They're cheap and most install in under an hour. Two things though: get one with a switch or add an inline switch, because you have to shut it off come summer or the compressor will run constantly. And older fridges from the era before 'garage ready' became a marketing term often handle cold better than new ones, since the old mechanical thermostats were less picky.

Or do what a lot of us do: unplug it from roughly December through February and use it as a big insulated box. It'll hold cold stuff fine with the door shut. Just pull the cans and bottles out first, since anything carbonated will freeze and burst and you'll be picking glass out of the coil area for months.

On the summer side, 90+ is mostly fine. The compressor just runs longer and the electric bill notices. Give it a few inches of clearance from the wall for airflow and blow the dust off the coils once in a while, garages are filthy. If you do go the heater kit route, test it before the beef goes in. Toss in a couple cheap frozen pizzas and a thermometer, wait through a cold snap, and check the freezer stayed near zero. Don't gamble a side of beef on an untested setup.

I've been running a hand-me-down fridge in a Wisconsin garage with one of those heater kits for maybe six winters now and it just works. Mine came on automatically with the cold, no switch needed, but I still check it. Taped an old dial thermometer to a bag of frozen peas in the middle of the freezer and peeked at it every week or two the first season. Peas are a good stand-in for how a chunk of meat freezes. Only other thing I'd say is mine sits on a scrap of foam board instead of right on the concrete slab, since that floor gets brutal cold and I figured the cabinet bottom didn't need to sit on ice all winter. No idea if it matters but it costs nothing.

One more option: a chest freezer. I keep one out there instead of a fridge-freezer combo, and cold garages don't really matter to it since the thermostat reads the freezer itself. If the room's alredy below freezing, it just stays frozen wheather the compressor runs or not. Mine's been through plenty of Minnesota-style winters without issue. Doesn't help with the cold drinks part though, so you could do both, or just keep the drinks inside and let the old fridge go.

Update: went with the heater kit, same route as the Wisconsin guy. Put it in a couple weeks ago and the freezer section has held steady through a few single digit nights already. Also did the frozen peas thermometer trick to double check, seems to be sitting right where it should. Kitchen fridge is unloaded and the side of beef goes in this weekend.