Jim,

This oil in coolant worries me. Did you thoroughly flush the cooling system after sending the radiator to the shop? If not you need to thoroughly flush the system including the block, remove the drain plug from the block so you can more thoroughly flush the entire system. Once flushed, run it a little with water only to see if you still get oil in the coolant. You said before that the system was nasty, this could be residue. Flush, Flush and Flush again. I hate to say it, but I don't think a blown head gasket would only have the symptom of oil in coolant it would be worse, but the chances of oil in coolant on these engines is not great.

The glow plug is probably not a big deal. Have you checked the bar fuse inside the glow plug relay. Using an ohmmeter to check pin type plugs doesn't tell you much, they can have continuity and still be bad. A number of times, I've changed glow plugs that showed good to the ohmmeter, but upon changing them made the car cold start like new.

Best of luck,