I can tell you what comes to mind when I hear each condition you describe: Oil on the spark plug: oil is being introduced to the firing chamber past either severely worn piston rings or severely worn valve guides. That would indicate you have a well-used and worn out engine.
Anti-freeze on the spark plug: Most likely a blown head gasket, however you didn't seem to indicate that the other plugs besides the first one had this condition. So there is a possibility that only the intake manifold gasket on that side is leaking coolant into the #5 (1st plug, driver's side) intake runner and contaminating only that plug.
Gas smell in the oil: often caused by fouled plugs (by oil, anti-freeze, carbon, etc) misfiring and allowing the unburned fuel to wash down the cylinder walls and into the crankcase and mix with the oil.
Only once have is seen a ford V8 engine blow both intake gaskets because a malfunctioning PCV system was causing high crankcase pressures. Generally oil will not be sucked from the valley into the intake runners through the leaking manifold gaskets, but because of the high crankcase pressures in this instance it did happen and the plugs were contaminated with oil and coolant and the truck had massive vacuum leakage.
Can't say that's your problem, but I'd have it checked by someone who is able to physically see and test the engine. Let us know.
Sunday, June 10th, 2007 AT 1:45 AM