>Would it be plausible?
Armor is maintained and operated in the middle of combat zones…it's plausible.
>Would it be plausible to maintain a modern tank after the collapse of society? Or would an old museum piece be a better choice?
A "modern" tank, which would be the M1 (or similar platform like the Leo 2, Chally 2, ect…) is going to be far too difficult to maintain and operate. They rely on extensive and well supplied logistical systems, most of their systems are very advanced and difficult to repair/replace such as the Fire Control System, Powerplant (engine), Navigational Systems, ect… The "Pros" you do have are far outweighed by the "Cons".
Additionally, you have to being into consideration Training and Familiarization (Fire Control System, Driving, Radio Systems, ect….), Tank Gunnery (the maingun and coax), Vehicle Maintenance (including electronic, track, engine, ect…)
Some of this can be tackled through obtaining manuals, but you'll need someone with experienced on armor to help you to train and become familiar. You need a 19K, preferably a Master Gunner.
Once you've accounted for the above; this is where you measure the hardware "Pros" and "Cons".
Something like the M5 Stuart as in your photo will run on simple Gasoline (Petrol), uses a 7250HP 7-Cylinder, Radial engine, 1/2-2in of armed plate, and is armed with a 37mm Gun and 3 M1919A4s.
Pros of the M5:
- Lightweight, meaning it's fast.
- Wide track placement, superb in muddy operationing conditions
- Gas, which simplifies logistics
- Simply 7 cylinder radial engine, easily worked on
Cons of the M5:
- It's weight is a detriment in certain enPost too long. Click here to view the full text.