2017 Malibu Hybrid questions...

There is a heat exchanger in the cast exhaust manifold intended to rapidly warm the coolant. The intent for this is unclear, whether to rapidly provide cabin heat or to rapidly get the little 109" engine up to an efficient operating temperature, or both. In either case, what are the options when this begins to leak internally? We all know that coolant contamination of the oxygen sensors will dull them down to a non-reactive state, and coolant in the calalytic converter will killl it fairly quickly. I see that GM already offers replacement manifolds, after only 3 years of production, so this may be more common an issue than anyone is letting on.

I've thought about bypassing, but thatprobably isn't the best option in the long term. At just over 50,000 miles, the local dealer isn't helping at all with the GM powertrain warranty.