In the past my water hoses had brass fittings--no problem disconnecting the hose. Current hose has aluminum fittings and when I tried to remove it, no luck even with pliers. Oiled it and waited till next day, bigger pliers still no luck. Haven't applied heat yet so don't know what that will bring. Guess if using aluminum fittings lube first might work but better yet avoid aluminum and get brass.

I learned this some time ago. When using hoses with cheap a$$ aluminum fittings never leave them connected to anything. Disconnect both ends after each use. My well water is very high in mineral content and Al fittings will 'weld' themselves in place in a day or two. You can buy some really nice brass replacements (McMaster) but they will cost about as much as the hose.
C.G.B.

Same thing here. So solid that I started to break apart the fittings and they still wouldn't give. "Weld" is a proper description.

Yep. Those aluminum fittings are a mess. First time you screw one on coat the threads literally with antisieze if you ever want to get it off.