What does it mean if you have oil in your air filter?
Check the PCV (Positive Crankcase Ventilation) valve. Failure in the pcv ? Usually it's piston ring blow by caused by worn piston rings. Get a compression check. I'll bet this has at least 100K miles on it. Its called "blow-by" you need to replace the piston rings. Over time the rings and cylinders get wore out allowing oil to go past the oil compression ring. Also check to see if there are bubbles on the dipstick to your oil,thats an indication of bad rings too, its gas in your oil. Check if your PCV (Positive Crankcase Ventilation) valve is ok