GM 350 crate oil burner

[8door]

I purchased a new 350 290hp crate built in Mexico.
After about 500 miles it began to use oil...... not a little ........a LOT.
About every 100 would need a full quart to fill it then consume that. I figured after another 500 or so the engine should be broken in... nope still oil out the exhaust.
Before firing I did all the spec things , pumped up the lifters and system by priming, ran 20 min at 2k to break in the cam, changed out the break in oil and filter watched the pressure and temp etc etc.
Ran nice smooth power overall ran very well except the oil.
After 1500 or so I pulled the rockers all 8 exhaust valve seals were shot.
The warranty is 100,00 mile or three years. but I bought the engine five years ago stored it in the factory packaging in my garage, so no did not contact GM. Whats the point.
I replaced all with Viton seals.... we will see........
Just wanted to let you all know to be aware of Mexico GM.
I do like my "American" built C10.