Civic - Honda :: 1998 - Overheating - Temperature Gauge Basically In The Red While Driving

I have had my 1998 Honda Civic for about 5 years now... I bought it used. Occasionally I have noticed my oil levels have been low every 2 months or so. Oil is not being burned and doesn't leak. It hasn't affected performance from what I can tell. I have basically monitored the levels and everything has been fine. There was also an electrical issue since I have had it.

About 8 or 9 months ago, I noticed the temperature gauge was basically in the red while driving. I pulled over and noticed the oil was reading empty. I put oil in it and took it to the shop the next day. They told me the head gasket was bad and that the oil and coolant were mixing and recommended I replace the engine. I asked them how long I could manage before the car quit entirely and he said maybe a month, two if I kept doing oil changes.

I put the heat on while driving it, and the temp was normal. I took it to another shop the same week. They couldn't get it to overheat for a couple hours. The guy told me it was probably the fan but wouldn't know unless he could see it overheat. He said the fan would cause it to overheat at stoplights when there wasn't air on the engine. When the car gets hot, it doesn't get worse at stoplights and is only after I've been driving like 20 minutes that it heats up. I asked that he call me as soon as he knew what it was and I would decide whether I wanted it fixed that day or not. Then I didn't get a call for awhile, and when I called them, they said the guy was out getting the part. I felt like they were rushing so I would replace the fan. I asked if it was the head gasket because I didn't want to fix a fan if the engine needed to be replaced. They said it was not. I didn't replace the fan. They also told my husband that we could save wear and tear on the engine by putting the air conditioning on instead of the heater. When we do this, it overheats. Its only when the heater is on that the temp stays normal.

I have been driving the car for 8 or 9 months now with the heater on with no performance issues. It doesn't overheat and even when I forget to put the heat on it goes up to the red, but doesn't "overheat" with the steam and whatnot. It doesn't seem to do anything to affect the performance of the car. We have replaced the radiator cap, which had pieces falling off, and it didn't work. The check engine light came on yesterday and the code indicated something to do with the transmission.

We took it to a third mechanic today and he said I needed a new thermostat... I do not see any sort of film in the oil. We just flushed the coolant today and there was no sign of oil. I'm totally lost on what to do. I feel like the mechanics have lied to me about what was going on. They contradict each other and the little things they told me don't seem to be the case or don't work.