Ari, I kind of agree with your assessment, but have some reservations. For example, even if the head gasket is compromised, where is the extra coolant going when the engine is hot *so that it can be retreived and go back in the tank as the engine cools?* It seems to me that it should go away for good, somewhere in the cylinders, or the oil, right? But oil is clean, there is no white smoke, engine runs perfectly fine, etc. So I am still at a loss to explain this.

Even though I don't want to do the work of changing the head gasket, I will probably plan to do it soon anyway. Have done it before and it was not my idea of fun. But, since I have the experience, I could proabably get it done in one day now, except for the part of having to send the head out to be resurfaced. And I do want to avoid a rental car, so may skip that part if I think I can get away with it.
--
Scott Cook - 1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)