Alright, I've filled the car up with DI water 3 times now and drained it and it still looks like there's a lot of oil in the water. It did start clearing up by the thermostat a lot though. The oil has a paste consistency and is a light tan color. The last time I ran the car, the coolant temp was stuck at 220 and wouldn't go up or down from that point. The oil temp was only around 180 when that was happening. Would a coolant pressure test help point where the oil is leaking into the coolant? Other than that I'm out of ideas. Oil looks perfectly fine still - might be losing a little bit of oil but the water is never going into the oil. The exhaust is also clear, with no white or blue smoke.

The only similar post I found was on the cobaltss forums where someone brought in a cobalt with oil leaking into it. They said it was most likely a cracked block and they just replaced the engine on it rather than diagnose it. How many more flushes should I do before I just pull the engine out and figure out where it's leaking?

I also have a pending code of P0455 - I don't think this is related to anything happening except that I unplugged the vapor canister and got a little oil on the connector from the thermostat. I did have a warning on the DIC a few weeks ago to tighten the gas cap so I think it's related to that. I think the fuel tank pressure sensor said the pressure was negative - anyways I think it might be the gas cap for that issue.

 

Tank pressure is supposed to be negative, how much is the salient part.

 

If I recall correctly, it was around -0.03mmHg, almost 0. might've read it wrong - didn't look much at it

 

That is far from zero. There are 760 mmhg in 1 atmosphere.

 

Well, I guess the question is - what should the pressure be for the fuel tank?

 

It varies. The EVAP tests know what it is supposed to be when the test is run. It is mostly a matter of rate of change when the valves are manipulated.
Save money Potable water is fine in the cooling system.

 

What's required for the EVAP Test to run? I read that it requires the car to get at highway speeds. I'm guessing P0455 won't need that to run though? Can this P0455 be related to any of the issues I'm having with the oil in the coolant?

I went ahead for the 4th flush and ran it for 40 min. Temp held up at 180 the entire time, and once I went to drain the water there was still a lot of oil at the radiator cap and thermostat. Might be a little less in the coolant now but it's pretty hard to get the oil out. It doesn't really drain out. All I can do is mop it out. The oil level has not changed yet.

If it doesn't start clearing up in the next flush I think I'm just going to start tearing down the engine to figure out where it's leaking. I know you guys mentioned earlier that it could be the water pump leaking oil but I still have no idea how I would diagnose that. Do you have any tips for how I could do that?

 

P0455 has nothing to do with oil. The P0422 test runs when the engine has been turned off after a warm up cycle. The po455 test is run as part of the p0422 test.

Just replacing the water pump would be cheaper than tearing the engine apart.

Is it possible someone is messing with you? I can't think of a way to get that much oil in the coolant. Maybe the head or gasket is to blame

 

Thanks for the clarification on the P0422 and P0455 tests, that helps a lot.
I wish someone was messing with me instead of having to deal with this, but no one has touched the car.
I guess I'll remove the water pump if it still doesn't clean out the next flush. I might be able to see if one of the gaskets inside it is damaged? Are the water pumps from ZZP good to use as a replacement?

 

I think he meant P0442, not P0422.