why is my airfilter ful of oil ?

Lonewolf is exactly right. It's just worn out.

The PCV system functions by creating a circular airflow path. One "end" is the vacuum port on the carb, the other "end" is the large hose that draws air off the aircleaner.

The vacuum signal at the carb port draws air from the aircleaner, through the almost never-cleaned valve cover inlet breather, through the crankcase where it picks up blowby gases, out the valvecover via the PCV valve and into the intake to be burned.

What is happening is that there is too much blowby for the PCV valve to handle, so the combustion pressure seeks another way out which in this case is the wrong way through the crankcase breather. So, all that oily mist is ending up settled in the bottom of the aircleaner.I bet if you take the oil cap off with it running it'll sound like the exhaust coming out of the oil filler.

You can band-aid it but that's essentially just figuring out how to hide the oil blowing out. I had a 231 Buick once that had so much blowby that it would ruin the air filter element in 500 miles. I ended up disconnecting the valve cover breather hose and extending it with a piece of heater hose down behind the front tire. After that any time I sat at a light there was a nice oily haze drifting up beside the car:D