Linux

With 8 GB of RAM and 5500 CPU passmark points, that's a good laptop for Linux Mint. Download their "edge" version of Mint, so you get the latest kernel (so it has more chances of supporting 100% that laptop).

ITT: Every distro

I use Debian stable on mine. I got 16gb of ram but tbh it’s never gone above six in real use, even with a windows vm running.

E: old thinkpad gang input: take the time to reapply thermal grease to the cpu at some point. It makes a huge difference.

Older Thinkpads are very well supported by pretty much everything, so it might be helpful to know more about your experience and what you’ve liked or not liked, and what you intend to run on it.

Linux Mint or Fedora aren’t bad options, Fedora will require a larger version upgrade at least yearly.

I think what matters most in your case is the desktop environment, not the distro. I would suggest something lightweight and fast such as Xfce with the distribution of your choice. Gnome and KDE tend to use (a lot) more resources than Xfce. I personally use Debian stable with Xfce on all my machines (which includes a Thinkpad x220), but the Xfce default settings are not ideal on Debian so you will need to fiddle with them (it can all be done easily with the GUI, but it isn't the most user friendly experience at first). If you want something that looks good outside the box that resembles Windows I would suggest Linux Mint Xfce Edition, very straightforward and easy to use with good looking defaults !

Debian. Hard to get more stable (to a fault, even) than Debian.

You can't go wrong with Debian or Fedora.

SLACKWARE!!!!

I agree with other users recommending Mint

Debian Stable or Testing. Runs on anything, and Stable - especially - will not let you down. Ubintu, Elementary and dozens of others are downstream of Debian. Bookworm is a great experience, so why not go to the source?

"Testing" is described as containing packages that are still in the queue to be accepted into Stable.

"Unstable" branch is all the newest stuff, whether it works or not.

If you're in school for anything computer-related, once you've settled on a distro, you could also start playing with Gentoo.

Any distro should be fairly stable and supported on an older Thinkpad.

I’m currently using Debian stable on my X220 and it’s rock solid.

I use Linux Mint and currently Fedora on my Thinkpad.

Mint works well on my Thinkpads

Will echo the recommendations of debian or mint. I have mint on my 13 year old rog laptop, it's my lab computer and runs klipper for one of my printers, pretty much always up, very rarely reboots. Debian is what I run on my 4 year old zenbook s, pretty much perfect for my uses, it's what I cart around for light/mobile work and I swear it actually has better battery life than it did running windows.

At this point in my life I would use Fedora Budgie/Xfce/lxde for a lightweight distro. Atomic or not. Lately I've been into atomic, but there are some scenarios and software I use that do not play well with the immutable OS.

Debian or OpenSUSE. Can't go wrong.

I think Debian unstable works great on laptops, and it's hard to beat for stability.

Fedora runs like a champ on em

Been rocking Debian on my 30 series.

Mint. LMDE.

First you need to explain what you want by lightweight. RAM, Disk, GPU, Pre installed packages? Features?

If you need to ask for a distro the answer is Mint, if you didn't need to ask the answer might be different, but then you wouldn't be asking.

I think it'd be helpful to understand why you want a lightweight distro. I'm running Linux Mint (Cinnamon) on a x201 (~13 years old) and am happy with it's performance. I doubt you're going to have any issues with any distro with your laptop (as others have pointed out, mainstream Thinkpads are well supported by Linux).

I know I have friends who run beasts of machines but refuse to "waste" resources on niceties like animations and whatnot. If you're into that, I assume you want to optimize and tinker, that's different that lightweight.

Last time I was looking for lightweight distros, I found antix & MX. Both are nice, lightweight debian daughters.

That was over 10 years ago. Still inclined to use them for distros to give to people wanting to exit Windows, though all the voices for Mint make me want to check it out, too.

Mint is always a good point to start when in doubt. Ubuntu is also solid and has lots of documents online.

I run LMDE 6 on my Thinkpad. Takes a bit of initial TLC to get tuned, but it's rock stable.

Cinnamon is a really stable DE, I've had almost zero issues ever with it. It's a little plain, but not ugly, and you can add themes if you really want to pretty it up.

Personally, I run OpenSUSE Tumbleweed on similar hardware.

I used antix for my laptop. Its the most lightweight. I also used Debian on it. Mine is also lenovo. If you want real lightweight use antix I guess.

I have been using a t450 for the past 5 years as my only pc. For about 4 years I used Arch without any major issues, but my “optimizations” became too much to maintan. For the past year I’ve been using Kinoite and it’s brilliant.

Everything runs good enough out of the box and in my daily use I haven’t noticed that I’m running a 9 year old machine. I even play games that should have no business running on that crusty old thing. Also, the stability is divine.

I'm using Fedora on a second hand x380 Yoga and it works rather nicely.

mint is nice but fedora KDE runs also pretty well on my thinkpad x1 yoga gen3

You can run any distro you like on it , but peppermint is is my favourite. Everything you need and nothing you don't.

Nixos

I have a similar ThinkPad, I run Mint with LxQt, though xfce is a good option too

I have a gen 6 x1 carbon which I read is similar. Popos runs a dream on it.

I have a T560 and i run debian with sway. It serves the dual purpose of getting me more comfortable in the terminal (i even use power shell on my windowa desk top a lot more now), and it runs much better than KDE or gnome did. Im missing some obvious quality of life settings like easily adjusting the power settings (it never sleeps, just turns off the screen and locks). But again, im trying to get more comfortable using the terminal so for me its more of a "take the training wheels off" thing.