It's definately a good idea to relace the gas valve with the newer
style ball valve (they're less than $10). The old valve like you have
is known as a GREASE PACK valve. It uses a special grease to lubricate
and make the final seal between the two ground brass pieces. Over time
the grease dries out and can leak.
Please ignore the advise you got to lubricate the valve. You should
NEVER oil a gas valve. It dissolves the grease and make it leak even
more. If it's hard to turn, that's proof that it needs to be replaced.
As far as problems turning off the gas at the meter and turning it
back on again, you run into the same problem since most older gas
company valves are also GREASE PACK. However, if you have a small leak
when you turn it on, the gas company will fix it for free since it's
on their side of the meter.
They loosen the nut, remove a plug and install a grease injector. Then
they crank the grease injector to push the old grease out while they
rotate the valve several times to work it in. Remove the injector,
tighten the nut, install the plug and it's like new.