I don't think there's any oil, but of course I can't be sure unless I take everything apart. I did have it apart about 1500 miles ago, and there was no oil. What little I can see through the bellhousing hole (where the shift fork exits) looks dry, although I'm sure it wouldn't take much oil to cause a problem.
At that time, the engine was re-done due to a broken piston, and of course a new crankshaft endseal was installed.
Engine is a Ford 428 with a Lakewood Bellhousing and a Richmond Gear 5-speed. Flywheel, presssure plate, clutch disc and flywheel only have a little over 6000 miles on them.
I have had clutch problems before (chatter) and I suspected oil contamination, but it turned out to be a leaky slave cylinder which allowed air into the hydraulics. New slave cylinder, bled the line, and I've had trouble free clutch operation all summer until just a week or two ago. Around this same time, we've had both high humidity and a lot of rain due to storms coming up the eastern coast. The weather is quite colder than during the summer as well.
Mind you, my standard transmission truck works fine, but it's kept outdoors and used every day. The problem clutch is in a cobra kit car and is stored, often for weeks at a time, in an unheated garage.
If the weather ever clears up for more than 1 day at a time, I'll try the clutch two days in a row and see if the problem comes back the second day. If it doesn't, then I'll assume moisture.