I use royal purple 10w-30 and wix/napa gold filters in my 05 yukon.
I just started using a synthetic oil sold at tractor supply for my squares, It`s under their brand name "traveller" and it`s $5 a quart.
I never use any no name oil so i did alot of research online to find out who actually makes it and an american company named Warren performance products makes it in Iowa and nebraska.
http://www.wd-wpp.com/index.html
They make oil for the big box stores like TSC and walmart and you can tell they make it by looking for the initials WPP on the bottom of the containers of the synthetic oil. for the regular oil it has different initials that i cant remember "sorry".
I change it at 5000 miles. I know they say you can go 12,000 miles with regular filter changes but no amount of convincing will ever get me to go that far. Oil changes are too cheap and easy to let go that long for me.