3.2 MV6 2003 auto 70k miles. In spring this year had custard in header tank,changed st steel oil cooler for a new st steel one.For a couple of months burped up a bit more emulsion then ran clear.Decided to give her a treat in time for winter so,flushed [stat left in],filled with tap water and rad flush,ran for few miles ,flushed,filled with pink concen and denatured water.Ran for 150 miles and header tank had a 5mil topping of sump oil.Changed oil no coolant present,header contents in clear bottle showed oil on top confirming prior observation.Have run for a couple of miles and seems to be continuing.Possible serious failure of new cooler??? Limited head gasket failure from oil lie to coolant gallery??? Usual practice advises bypass of cooler but this seems difficult with the rigid pipes used.
Any advice will be valued as 2G for repair of head gasket is not poss.