So I got a 92 Laredo 4.0. 146,000 miles. One owner before me, my gpop. Sense he bought it new he always put in high quality full synthetic oil and was **** with routene maintenance. I have continued to do full synthetic 10-30 with high quality filters, but do run it somewhat hard. It's never consumed oil untill now all of a sudden. I have a cone filter on it and a full cat back w/out a cat. I know the pcv system is clear. Just put on a new pcv elbow thing and a small clear fuel filter inline just to see if that's where its drawing in oil.



As you can see its not drawing up much. The intake tube and throttle body are clean and clear, no oil residue. It only burns it when its warm, and has been idling for a while, then I hit the gas and puffs out blue smoke. Just added 1qt of oil. So far I'm thinking the only real reason would be piston rings. I would think valve stem seals, but when its warm if it shut it off, wait a couple minutes then start it up, it does not puff a lot of smoke out. If the valve stem seals were bad, usually a tell tale sign is that's when it smokes the most, at start up after leaking down the valve. So I'm kinda thinking at idle the cylinders load up with oil, then start leaking past the rings. Is that correct thinking?

 

My guess is that your valve stem seals are hardened and shot.
They can be replaced without removing teh cylinder head.
A leakdown test will verify if the oil is going past the rings or valve stem seals.