The Gold Syn Blend is listed on Pennzoil's website as available in 5w20, 5w30 and 10w30.
According to the Dexos1
list online, there is also a 5w20 and 0w20 syn. blend available that are dexos approved, however, I don't see these on Pennzoil's site yet. My guess is as 5w20/0w20 is becoming more common in GM vehicles, you'll be able to find the 20wt. in the future with a dexos label.
Since (AFAIK) 10w30 isn't the recommended weight for any new GM vehicles you're not going to get a 10w30 on the Dexos List (but Pennzoil does apparently make the syn. blend gold in 10w30).