GAH!
Oil shouldn't be conductive! What kind of spray was that?
For what it's worth, there was a real problem in some older sets with carbonized (burned) circuit boards. I think it was the early rectangular Magnavoxes, you know the chassis that looks like RCA at first glance, yet is pretty different when you start looking close at the boards? Well anyway it happens. As I recall it is the grid pins that really matter. A little leakage will grossly mis-bias the tube.
If you look at the IF board in the CTC-15, the board is milled out at the grid pins, and there are flying leads to the tube socket. I have often wondered if this was to reduce capacitance, or if it was deliberately done to prevent bias problems from carbonized boards.
Does your board look carbonized? Do I understand you correctly that all connections are removed from that trace and you still have a meg to ground? How far is the trace physically from ground?
John