No, O2 sensors are to clean up the emissions. If you have a gas smell, I would suspect fuel lines, or a gas cap.
your vehicle may smell like antifreeze while driving because it is overheating
It is possible it is one of the speed sensors.
Some are and some aren't. There are different variations of oxygen sensors. First you have narrow band and wide band O2 sensors, then you have heated and unheated O2 sensors. Unheated sensors can have 1 or 2 wires , while heated sensors can have up to 5. Also some sensors are specifically calibrated to the unit they are intended for, so unless you really know what you are doing, then no they are not interchangeable.
I believe you are seeing your Oxygen or 'O2' sensor. It measures the ratio of oxygen in the exhaust and sends the info to your car's computer while you are driving. If the O2 sensor is bad your car can run poorly. It is one of the more important sensors on you car.
Find the leak, and fix it. theirs no leakge bra.
over years and years,yes...but it has to be sitting, not running...and it would take a while
Obviously you have a fuel leak somewhere.
There are 3 oxygen sensors; one in the front exhaust manifold, one in the rear exhaust manifold, one AFTER the catalytic converter. The 2 exhaust manifold sensors are the same BUT the catalytic converter one is different. Also, the 2 exhaust manifold sensors have heaters in them, while the converter one doesn't.
Probably not the oxygen sensor. I'd check the wheel speed sensors first. Possibly even a wheel bearing.
The upstream is screwed into the front of the catalytic converter, while the downstream is screwed into the pipe after the converter.
A common cause of this is a faulty or incorrect oxygen sensor. A lot of the cheap aftermarket sensors will do this, especially the cheap Bosch ones they sell at many parts stores. Denso is the OEM brand.
Erratic RPMs while driving or in park could be due to a faulty oxygen sensor. It is also possible that poor gas is being used.