Unfortunately "OZ" is not a valid word in Scrabble. The only valid two letter Scrabble word is "ZA", which is apparently a pizza!
Two letter words can be the key to successful Scrabble playing though, so here are some more high scoring ones you may not be aware of (along with definitions because you will undoubtedly be asked to explain what they mean by your opponents!):
QI - "The vital force that in Chinese thought is inherent in all things"
XI- "A Greek letter"
XU- "Monetary unit of Vietnam"
KA- "The spiritual self of a Human Being in Egyptian religion"
KI- (A derivative of "Qi")
EX- "To cross out"
I guarantee with these in your weaponry, you will be a force to be reckoned with on the Scrabble board!