Re: Yes - that is probably a very common issue
I've fought the issue for some time. It's my opinion that there is a very small crack in the head gasket---so small that it's not detectable by block testing kits. It takes about 8-12 months. Coolant is burned off, and some air develops. I elevate the nose, open the bleed screws while car is running, turn the heater thermostats to max. Then remove the bleed screw at the thermostat and add coolant through that bleed opening until full. All will be well for another 8-12 months.