mazda mx3 percidia '94

My car smokes on start up but only for 1-2 minutes. I've had the compression checked and it's fine. There is no sign of anti-freeze in the oil. My mechanic thinks it might be carbon build up. I drive 200 km a day highway(120 miles). There is 365,000 km (200,000 miles) on it. Someone said that might be the valve guides pluged up I think. Don't know what this means or how to correct it. Any thoughts or suggestions are appreciated.