Hi,

I have a 99 civic coupe EX with a 99 Jdm GSR engine in it. I recently noticed that the car was running rich. The tail pipe was laced with black dust (inside).

So I suspected a bad O2 so I replaced it (the one on the header) and am thinking of getting the one on the catalytic converter done too.

But I have notice a significant drop in oil. From one day being full and 3-4 days later completely dry.

I just replaced the O2 2 days ago and the oil has not been dropping drastically so far during 2 days of both normal and aggressive driving.

I use Mobil 1 race oil. and premium gas either 91 or 94 octane. The gas mileage went down as well. Prob 300km-350km a tank.

Have been looking under the hood and under the car, no visible leaks at all. the engine does not overheat. The sparks plugs have a bit of white layered deposits with the ring laced with black carbon deposits but not on the grooves.

Can a bad O2 cause an engine to burn oil ??

My catalytic converter is prob done should I replace it?

No blue smoke so far.

Thanks in advance.

compression tests on all 4 cylinders were very close to 210 on all 4.