I've got coolant in my oil & oil in my coolant. Very little swapping going on right now, but it looks like something serious is just getting starting.

At this point I'm hoping to JUST change the head gasket. Other than the head gasket, a cracked head, or a crack in the block is there anywhere else an '03 MCS might swap it's fluids... heat exchanger at the base of the oil filter canister, etc.? Even the best case ain't looking good.

 

My 05 needed a head gasket at first. Then they noticed the head was bit warped. BMW thought the best course was to replace the entire small block and not just the head.

 

Unless you've overheated, I'd check the oil heat exchanger first before pulling the head.

 

I think I've ruled out the oil heat exchanger. I disconnected the hoses and coupled them together to just bypass the exchanger, and drove it a few times. My rate of coolant loss didn't change at all.

One thing I did do that I've never done with this car was remove the oil filler cap while it was idling. The pressure blowing out seems pretty excessive, and there is a VERY strong smell of exhaust gases.