I just heard on trucks 4x4 on Spike this weekend that oil burning is caused by the rings. But the rings only fail due to the different expansions rates of aluminum and steel.
The guy I talked to was at Engines Direct....they currently have some remanned 6VE1 engines on ebay...and apparently sell remanned engines across the Country to numerous dealers, etc
He mentioned they had to replace the stock rings with a different type to fix oil burning.....
Their crate engines are all new parts with upgrades for $3400 less core of $425, shipping is $150.....warranty 3 yrs/unlimited miles
Here is their 800 number: 1-800-998-2100