Minimum Level

[kwschs]

Whats the min lvl to enter SM GY

[Quix]

20 for all SM Instances (they are technically the same instance.)

[kwschs]

dam dont know why im still in WC haha!

[Stealthy]

Bear in mind there is an exp cap for mobs higher level than your toons - have a look at this:
http://www.wowwiki.com/Formulas:Mob_XP

Cheers,
S.

[Simulacra]

Whats the min lvl to enter SM GYwowwiki is your friend
http://www.wowwiki.com/Instances_by_level