So I searched the forums to see if I could find this out, but no luck.
I'll run down the scenario.

1. 2 weeks ago: Noticed coolant was a little low in the reservoir. Added distilled water to get it to the full line. No external leaks. Oil looks as it normally does on the dipstick. Just below the F. Coolant looks good. No smoke coming from the exhaust at anytime.
2. 5 days ago: Coolant down to the low mark. Added distilled water to put it back up to top. Oil looks the same, no smoke, coolant looks good, no external leaks.
3. This morning: Coolant down to the low mark. Added distilled water to put it back up to top. Start it up and smokes for about 10 seconds. A lingering white smoke with a bluish tint to it. Exhaust smoke does NOT smell sweet. I drive it for about 30 miles, no more smoke, coolant level goes up a little(guessing normal once car is warmed up). Oil looks good, no external leaks.

What confuses me is that the car still runs excellent. No signs of sputtering, low idle, gas mileage decrease, etc.

Let me know what you guys think. 155k on the car now. I am in an apartment complex so I don't have the resources to diagnose, and don't want to drop a ton of money into it.

Thanks in advance.

 

I had the same problem with the coolant being low. I always refilled it once every morning for a week. Then I floored it on the freeway ramp and the head gasket blew. My car was at 153K at the time.

 

So for the past few days I haven't seen as much of a coolant loss, and it has not smoked at all in the mornings. Seems to be running right, and i've been driving it a good amount.