small oil leak

[Ford EX SPRT TRC]

I've got an 03 Sport Trac XLT. 72K miles.
When I park it in my driveway it's on a slight incline and is leaking small amount of oil. It seems to be coming from the back of the oil pan. However, the truck does not leak when it is parked on a flat surface. Just checking to see if any body else has had this issue. A buddy of mine thinks it may be the main rear seal. Anyone know how much that is to replace?
Thanks,
Marty

 

[Kjhadfield]

That's sounds similar to mine, parked on incline. I have a thread I posted photos asking the same thing and it had some good possible causes and suggestions that a small leak wasn't to much cause for concern (I'm at 164k thou)

 

[Kjhadfield]

http://www.explorerforum.com/forums/showthread.php?t=418670