I mostly ask this question because of "All Star Superman" I watched the movie, but didn't read the comic, and in a scene when Superman is lifting a heavy object, appearantly he was lifting up about 1 Trillion tons or something like that. (I don't exactly remember, but I knew it was alot) the biggest thing I saw him lift up (or at least pushed) was a planet. I just think DC made him way too strong and way too powerful
And yet he can still lose.
Don't forget he has Ice Breath, Lasers from his eyes, He can hold his breath for who knows how long, Super Speed, Agility I'm sure, X-ray Vision, and Super Strength.
How much can he lift up? I have no clue...and i'm sure it's ALOT!