Castrol synthetic or Valvoline?

TrailBeast said

After running the 5.9 Magnum for 9 months and finding it uses ZERO oil after 10,000 or so miles I am going to change to a full synthetic oil.
Thinking to go with a 10-30 full synthetic in the Castrol or Valvoline line.
I have run and trusted both brands for decades and was wondering if anyone has a preference between the two in synthetic form and why.

Also, I am a little apprehensive about going thinner like 5-30 or 0-30.
Would there be any good reason for oil that thin other than better heat transfer?

Switching from Castrol Dino 10-40 and I use the black Napa Wix/Mopar filters.

Thanks

Click to expand...

I wouldnt run a zero weight myself, Back kn the days of Mobil1 it lowered the idle oil pressure to ziltcho once its heated up real good, Everytime you come off the freeway of 5 min or better the idle oil psi will go from 35 let's say ...to 10-12 maybe and for 1 hp in the rpm range you actually drive in.jmo I stay no less than 20w myself.
when I want valvoline, I pay less and get it in a Napa bottle.
I have had really really good luck with para synthetic oils like Schaefer Supreme 7000, I put in every motor, customers and my own now for 18 years. I never lose cams after break in, not one of them has blown up, and lower oil temp/engine temps by average 4-5 degrees. You can run almost any oil you want in a motor and the difference between then can only be seen in the diff in lifespan miles, amount of wear seen in tear downs....or under the microscope where youll see less metal ppm in Schaefers after run than most any other oil.