Which synthetic oil to use?

[HUMMERcustoms.com/TAZ]

I hate to bring this subject up again but my request was burried deep into other topic.
You experienced guys with synthetic oil please advise me.
What synthetic oil should I use in engine, tranny, and differential. It seems most in this site is using Mobile 1 and I believe also Amsoil. My son inlaw love's mobile 1 syn. Would everyone give Me recomendation as I have never used syn. but, feel after being on the forum for little while now that since I'm coming up on 6000 miles I go synthetic everything on 3rd service. My H2 is not My everyday driver so it has taken almost 7 months to get to 6000 miles. I plan on given My Girl the best. I worked extra and saved to get Her and will drive it many years.
I will appreciate Your guidance. You make less mistakes when You get direction from someone that has already been through it.
Thanks
Rick

[HUMMERcustoms.com/TAZ]

I hate to bring this subject up again but my request was burried deep into other topic.
You experienced guys with synthetic oil please advise me.
What synthetic oil should I use in engine, tranny, and differential. It seems most in this site is using Mobile 1 and I believe also Amsoil. My son inlaw love's mobile 1 syn. Would everyone give Me recomendation as I have never used syn. but, feel after being on the forum for little while now that since I'm coming up on 6000 miles I go synthetic everything on 3rd service. My H2 is not My everyday driver so it has taken almost 7 months to get to 6000 miles. I plan on given My Girl the best. I worked extra and saved to get Her and will drive it many years.
I will appreciate Your guidance. You make less mistakes when You get direction from someone that has already been through it.
Thanks
Rick

[HUMMERcustoms.com/TAZ]

I hate to bring this subject up again but my request was burried deep into other topic.
You experienced guys with synthetic oil please advise me.
What synthetic oil should I use in engine, tranny, and differential. It seems most in this site is using Mobile 1 and I believe also Amsoil. My son inlaw love's mobile 1 syn. Would everyone give Me recomendation as I have never used syn. but, feel after being on the forum for little while now that since I'm coming up on 6000 miles I go synthetic everything on 3rd service. My H2 is not My everyday driver so it has taken almost 7 months to get to 6000 miles. I plan on given My Girl the best. I worked extra and saved to get Her and will drive it many years.
I will appreciate Your guidance. You make less mistakes when You get direction from someone that has already been through it.
Thanks
Rick

[HUMMERcustoms.com/TAZ]

I have always used Penzoil 15/40W in diesel got 265,000 out of it and used 30W Penn on last gas truck chevy got 230,000 on it.
I guess finally having the truck of my dreams I just want to go that extra or what I perceive as the extra mile for it.