mercedes has water leaking thru what my mechanic believes is a warped head due to overheating. Would this be a place where I could try one of the stop leak products? Of so, which one would you recomend?
Which engine are we talking about?
Those stop leak products are very unlikely to help if the head is really warped.
Do not use stop leak!! It will not help and could plug your cooling system. If your mechanic cannot verify the leak is from a head gasket find a new mechanic. If it is in fact a head gasket / head problem get it repaired correctly. I understand this job will not be cheap but it will cost more in the long run if you do not fix it properly NOW!