What is "a LOT of oil?" How many miles per quart? This matters.
How many miles on your Metro? This also matters.
1) I do not recommend "heavier oil." If the engine is burning oil, the engine seals have nothing to do with it. Burning oil means the piston rings are worn.
Seals prevent leaks at things like the crankshaft, the camshaft, etc. Seals prevent oil from leaking from the inside of the engine to the outside of the engine. Worn seals can leak oil, but they don't burn it.
If the engine is burning oil the rings are the problem, not the seals.
2) "Warped engine?" What the heck are you talking about? There are certain thing that might warp. The aluminum cylinder head is one of them, but you're not describing symptoms of a warped head.
Forget this "warped engine" theory. It's not the problem, either.
Additives are a waste of money. NONE of them do anything.
So, back to square one. How many miles on the car, and how much oil is your Metro burning? Does it leak oil? If so, how much?
Have you tried replacing the PCV valve? A bad PCV valve, which is cheap to replace, can increase oil burning when there's nothing else wrong.