I did learn some neat tricks now that I'm working for Honda. First thing is to make sure the thermostat is opening. When this happens, the LOWER radiator hose becomes hot. It should be equally (or damn near close to) as hot as the upper. You'll know the thermostat is opening. Otherwise it might be a clogged radiator, or a blown head gasket. I worked on a 94 Civic last week with the complaint that on freeway driving, it won't overheat. But when you pull off at an offramp or what not, the temp starts to climb. I found out that it's most commonly caused by a blown head gasket. I pulled the spark plugs out and looked into the cylinders with a light. Sure enough, there was coolant in #1 cylinder. So now I have the head off, awaiting authorization to do the repair. But check that thermostat, and pull your plugs and look in there to see if any coolant is present.