I have no idea what this engine has for a crankcase vent system. It probably has a PCV valve or some such.

Since the car is apparently driven only on very short trips I strongly suspect that there is some problem with the crankcase vent system. It may need a PCV valve and/or cleaning of the vent system.

When you are driving a car for short hops, say five or ten miles and never more, you really should be changing the oil and filter every 3 months rather than based on mileage intervals. The acids and moisture can build some really nasty sludge inside the engine.

Good luck,