No matter what you choose, just don't use Pennzoil for anything. I've had that validated by mechanic's throughout my life. I'm pretty sure Valvoline wins in my 40+ years of life. As far as Marine stuff, follow your service manual to the tee. Spend the money on maintenance, because repair costs way more if ya have to hire it out! Use synthetic in your gearboxes if ya can.
That may have been true 50 years ago but it simply isn't now.........The name on the can is not all that important any more as long it's an API "licensed" oil........... Cans with Pennzoil on the outside might have Chevron, Shell, or BP, etc.... base oil stock and a Lubrizol additive package......