My air filter on my 92 Mercury Topaz keeps filling up with oil. What would cause this?
You have a lot of blow-by from your engine which brings oil up out of the crankcase through the breather. What that means is your engine is probably worn and likely has high miles.
Regrets is right about the blow by but you should check the PCV system, if the PCV Valve is plugged or its vacuum source is damaged or nonexistent you will also get this same problem no matter how many miles you have on the engine, these engines are known to plug up the lines right at the base of the throttle body where the main vacuum supply is for the PCV Valve, so check it over. HTH