blue smoke and losing coolant
my 2006 f350 with the 6.0l has been blowing blue smoke lately- not when idling, it seems like mainly when i first start driving, it increases when accelerating, but will usually fade away after a few miles. it will occasionally blow again even after the engine has been running. i should also add that is likes to blow white smoke too, the blue smoke is a more recent thing, sometimes it seems like a combination of the two because it will be a lot of gray smoke
also this morning on my way to work noticed the heater wasn't working. checked coolant and it was bone dry. filled it all the way to max, and a few hours later, it was below the minimum line on the reservoir (when it had just been sitting during that time). heater was working again, but blue smoke was still there.
mechanic friend checked some things, engine oil was fine, no coolant in there, and he couldn't detect any coming out the exhaust. he said to keep monitoring the coolant levels and oil for a week or so and see what happens.
i'm afraid i have a huge repair cost in front of me. any ideas on what this could be? i am not mechanically minded by any means, so "laymens" terms would be appreciated.
i am weighing my options right now- i can't afford thousands of dollars in repair costs and if that is what i am facing, i still owe a few grand on it, and not sure what to do at this point. i am taking it in for an oil change next week- it is 1000 miles overdue, and will have him check some things out for me