7 quarts when changing the filter
Your choice. GM does not specify which to use so it is up to you. Just make sure to use the recommended weight.
You can use Synthetic oil at any time. You can even mix it with regular oil. Just be sure and use the correct weight.
R-134a
I use it on my 06 trailblazer I6 4.2
5w-30 oil. Most of our members use dino oil and many use synthetic. Oil analysis from Blackstone labs shows that the Oil Life Management System works very well and 8000 mile oil change intervals are very common. www.trailvoy.com
5w-30 dino oil or synthetic. Follow the Oil Life Management system on the truck as described in the manual. www.trailvoy.com Trailblazer enthusiasts forum!
I have a 2005 trailblazer and it recommends a multi-grade oil for the enine. Mine is 5W-30. There is not much difference in the multi-grades like 5W, 10W and such, but I would stick to a Multi-grade of some sort.
7 Quarts
GM tends to recommend 5W-30 oil.
As listed in the manual 5w-30.
Mine says 5w-30 on the oil filler cap
You can use either 5W30 or 10W30...doesn't matter