dont even bother with blends.
while they tout the "best of both worlds" and they do offer properties of both regular and full synthetic, however, they arent advantageous. and for the price you will be paying, switch completely to synthetic.
also you need to make sure you are using a good filter.
as for synthetic oils, I recommend Royal Purple.
Mobil1 and Amsoil are also good oils
for filters, I use a Wix filter or K&N filter, mobil1 filters are also great, but the M1 and KN are higher priced.
when you get about 200 miles before you do your next oil change, you should seafoam your car
http://www.ls1tech.com/forums/showthread.php?t=534376
reason being, swapping directly from dino oil to blend or full synth, you dont always get all the old oil out and they dont mix well.