OP this is good info they're all saying here.
I bought my little girl in Aug 2012 with 66k miles on her and went ahead and changed out to Ford Synthetic. It says use 2.1 quarts (and it's like $23 a quart) so I just bought 2, drained on ramps until it was running still but starting to drip, put 2 quarts in and it started to run out the fill hole (as it should if you've put in enough) so I quickly finished up and put the screw back in. 8k miles later and she's shifting like a dream.
Filling it though is kind of a b*tch! I had to actually get two clear rubber hoses and piece them together so I could stick one end in the fill hole and run the tube up through between the front bumper and the motor to fill. I couldn't get the bottle high enough to pour underneath w/out doing this but it actually worked really well my way.
06 maroon ZX4
2.0 Duratec - MTX75
35% tinted windows
plasti-dip wheels & grill
lunchbox delete - stealth CAI w/ AEM filter