As some of you may know, I've been having a few issues with my car in the past month.

It started when my engine overheated 3 weeks ago. I stopped the car immediately and had it faltbedded to a shop. The shop found oil in the coolant tank, did diagnostics and replaced the water pump and the thermostat.

After that, I took the car out and drove her for 4-5 days without any problems. Then engine started misfiring and it turned out to be the first ignition coil (first cylinder is the one that's furthermost ahead, closest to the oil filter housing).

I've been finding some oil residue in the engine bay up ahead for some time now, a long time. I've had the engine washed when the pump and thermostat were changed, but now I see no traces of oil anywhere, just minor sweating here and there. I suspect that the oil residue in the engine bay is caused by a faulty gasket on the heat exchanger or the exchanger itself. Because I regularly have my engine oil tested by the Blackstone Labs and the results always come back peachy as could be - their techs always tell me that the oil comes back better than most engine with my mileage.

Now the car is running fine - after the coil got replaced. No sign of trouble. Well, almost. There's still oil in the coolant tank. It isn't "bad" bad - my tech said I can even use the car for short drives in the neighborhood; like, its not severe. He says that if the problem was serious, the oil and antifreeze mixture would turn light grey under the temperatures and pressures that are present in the engine itself. The fact that oil is present in such small quantities and is not "mixed" with the coolant, to him, indicates that most likely it is the oil heat exchanger and/or it's gaskets, that are to blame.

I have a few days before he has an opening to get my car back in to do the heat exchanger job, but I wanted to post this thread and see what everyone thinks?

Sorry for the long post.
related threads:

My Original "engine overheated" thread

OIl Filter Housing Gasket thread