The engine oil will need to be changed a lot more often – at least until signs of condensation goes away.
When you drain the oil, try to drain it into a clear container. If you are getting coolant into the engine oil. There will be a puddle of it on bottom of container with the engine oil on top.
Also, when you drain the oil, you will see the water/coolant drain out first, then the engine oil.
A working PCV valve, crankcase vent, working heat riser, a not-too-cold thermostat as well as longer trips can help a lot. If you are driving 12 miles on at least one leg of your trip to/from work, then that shouldn’t be the problem. I recommend people to at least drive 8 miles (13km) on at least one leg of their daily drive – but if thermostat is too cold, that won’t work.
I know very little about mineral oil so that might be a possible issue (not sure, me shrugs).
The main reason to use petroleum-based oil is it and gasoline comes from same source (crude oil). I know those who race with methanol for fuel, use castor oil for engine oil (not Castrol oil company, but oil from the castor bean) – because the oil and fuel will mix if two come together and not create sludge or a mess.
Head gaskets can blow and leak coolant into the cylinders, leak coolant into oil or leak compression into other cylinders. Head bolts do not normally loosen up on Chrysler engines made in that time – so re-tightening them generally won’t help.
Also, smell the cap and see if it has a “coolant” smell to it. Has coolant level been dropping in radiator?
If coolant loss hasn’t been noticed, then I doubt it is coolant.
If coolant is getting into oil, then a leaking gasket, cracked block (or head) or porous block casting (or head casting) could be at fault.
BudW