I own a 2008 G6 V6 SE with the 3.5l v6, and was wondering if I should change the oil the oil % dic info, or every 5000 miles? I'm currently using gm'* new full synthetic, was also wondering which type spark plugs does this engine use, and when should I change them? Any info on e3 spark plugs?

5,000 is better than waiting for the computer to tell you.

E3 spark plugs are a gimmick. Get ACDelco.

That was kind of what I thought too! Thanks for verifying that for me. Maybe you could answer one other question I have. When I took ownership of my G6, it had 105k on it, and I'm sure my father ln law used conventional oil in it. I did 1 oil change with gm'* new full synthetic. Since I'm changing it every 5k, would it hurt anything to go back to conventional oil? I've had good luck with valvoline, any advice would be greatly appreciated!🚘

With 5K intervals conventional oil works just fine.

Yeah conventional works well, but for the 10% premium I always use synthetic.