Greetings to you all and thank you in advance for reading my question. I've got a 98 civic ex coupe.200k miles. Due to ruptured hoses twice over the last two years the car did overheat but not severely. After some hard drives to get to work on time I noticed a warm up of temp. Turned interior heater on to help cooling but hot air did not immediately come out though eventually it did. While at a stop sign I could smell exhaust from under the hood. Once home the reservoir tank was black and oily. I'm thinking that was the exhaust. Blown head gasket probable but no coolant in oil. Did a poor mans head gasket change by disconnecting most things from the head, removing valveset, and lifted head up of block enough to clean. Did straight edge test and head looked good. Put everything back together with correct torque values. Car is running fine still no coolant showing in oil. No exhaust residue in radiator or reservoir and the coolant is not dirty with exhaust, but the coolant keeps disappearing from the reservoir I have to put in about 4 oz every other day. No apparent leaks and don't get that sweet smell of coolant while driving or parked. Some have said radiator cap but it's only about 2 years old from autozone. If it was the radiator cap, wouldn't I see coolant around top of radiator or at least smell the common coolant smell? Just now did a block test with blue liquid that turns yellow with exhaust. Did test with reservoir tank closed and tester at top of radiator since the tool will not make a good seal at the reservoir bottle. When squeezing bulb, I had a hard time getting air to come through tester. Then took hose out of reservoir and then air would come through tester and never turned yellow. Took tester to tailpipe to test liquid and with exhaust out of tailpipe liquid turned yellow. I just don't know where the coolant is going. All your ideas are welcome. Thank you again.