'96 with a 3100 using a lot of oil

Hi all,

I had to swap out my 3100 last march with a used engine. This engine is supposed to only have around 90K on it. The issue I have, is after the initial swap, I drove it about 2K miles and the "low oil" light came on.
It was right, I put about 3 to 4 quarts in.
Now, It seem that every fill-up (around 350 miles or so) I have to add a quart or two.
There is no visible leaks, everything looks dry. When I first start it up, the exhaust is clean. While driving, the exhaust is clean.
I did the manifold gaskets during the motor install, and the coolant is still clean.
Any ideas on where to start to chase this down?
Thanks in advance!

Internal problem if the pcv is working and is the correct one, then possible valve seals then major internal problems, it is possible that the intake gasket is sucking up some oil, but only removing the lim will tell you that.

Check engine for external signs of leakage. Start from the bottom and work up.

Thanks,

Outside of engine is "dry as a bone". A little oil in the PCV tubing, so I will change the PCV and see......