Park the engine bay over a nice big clean sheet of cardboard or plywood, see what leaks turn up.

Perhaps as merc225hp pointed it's just normal usage.

 

The only leaks underneath is from my tranny pan.. I changed my fluid n filter a month ago and the pan was warped from over tighting and it was leaking badly.. I took it off and used RTV but not enough and so it has a very slow tranny fluid drip but not enough to bother me so I left it alone..

No oil drips on the pavement when its parked.. but I do see oil on the bellhousing of the tranny by the inspection plate and its all over the oil pan on the opposite side of the inspection plate you know where the engine and tranny meet? so my rear main is leaking but whats odd is it doesn't leak sitting parked... I wonder if it leaks when it hot and all warmed up.. And as I said my valve cover gaskets are brand new felpro.. I used to have leaks from the valve covers but that's fixed.

I'll get some spare cardboard and place it under the engine and see if it really is dripping or not. good idea

 

My old 99 used a qt every 400 miles, but still had good compression and power. Valve guides were shot and was getting a lot of blowby. Another way to to ,see if valve guides are worn, is hook up a vacuum gauge to an intake port. If the needle flickers you have some wear. Sounds like just normal usage.