Don’t pour hot grease in a glass jar or it’ll shatter and spill hot grease all over your counter and then when you grab a flimsy piece of plastic from the recycling and try to push it on to stop the spill and the plastic collapses and hot grease goes all over your forearm and gives you 2nd degree burns and your floor is covered in broken glass you will regret it.

I’ve been pouring hot grease in glass jars for decades without having one shatter. You’re severely overestimating the risks

It depends on where you’re from, glass jars/drinking glasses in Germany don’t shatter from thermal shock, but they do in the US.

I reflexively yelled at my boss once because he poured recently boiling water out of a glass and turned the cold faucet on to rinse it out while scrubbing, and I thought he was about to cut the shit out of his hand. He got contemplative for a moment and then said that he had forgotten that that used to happen in Afghanistan (where he was from), but it doesn’t happen in Germany.

Just putting oil in a few dozen times won’t shatter it. A few hundred cooling cycles might, but you change jars by then.

It won’t necessarily shatter it, but it absolutely can. I’ve done it with a jar I had washed the original product out of shortly beforehand. Just because it’s never happened to you doesn’t mean it doesn’t happen.

I guess it depends on the temperature of the oil, I pour when its still liquid, but less than boiling.

I pour when it’s hot to the touch, but not unpleasant, so probably around 50-60 C

And it still shattered?

Yep, I was PISSED. I can’t even eat pork and was just being a good houseguest the morning after a party, and then suddenly had to clean up a bunch of shattered glass and pork fat in someone else’s kitchen.

Canning jars are made to withstand temperature changes though.