Can I use this jack on a concrete floor or does it need a solid lift pad?

Always place this jack on a solid, level surface — concrete garage floor is fine, but soft ground or asphalt can cause it to sink or tip. A steel jack pad under the base gives you extra safety margin on any surface.

What maintenance does a welded steel bottle jack need?

Keep the hydraulic cylinder clean and dry, wipe the rod after each use to prevent rust, and store it in a dry space. Check the hydraulic fluid level periodically — top off if you notice slower lifting or leaking around the pump head.

Is this jack safe for supporting a vehicle while I work underneath?

Bottle jacks are designed for lifting only, not holding. Always use jack stands rated for your vehicle's weight before going under the car — never work under a vehicle supported by a jack alone.