hmmm I don't own an Ecotec but from my understanding, any plugs that under $2.00 is not worth putting into a car, honesty.
Secondly, its doesn't really matter if you want to use synethic or regular motor oil. if you use Mobil 1 syn 0W-30 then I would advise you to when it 3000miles change the filter, you may not need to change the oil if its still clear, but you may need to top it off. If you get Wix from O'Reilys those filter are really good and cheap. You can ask them to show you the cutout and compare a Fram, Bosch, MotorCraft, and Wix oil filter. You will see the difference in the qaulity of the filter.
Heres a link to
60 degree V6 for more info on oil change.
P.S. Sorry to bring back a deead topic