[wolfdog46]

I have had several thermostats stick closed. When it is running hot did you notice a very steamy exhaust? I had a chevy with a blown head gasket it never got water in the oil, just a VERY steamy exhaust. If it were me I'd do a Thermost change first. If still haveing trouble, radiator flush next. I presume that you checked that you don't have a leaky freeze plug. And if any of that is not your problem, I'd put a new head gasket on first as I think it would be less time consuming & less expensive.