For my small boat I run Mercury's Quciksilver 25W40 Synthetic oil.
It costs more but sure beats issues with the oil thinning out on hot summer days.
You can use regular automotive oil in the boat but I stick with the Merc oil for peace of mind.
The bigger boat I let the dealer service it so I have no idea what type oil they stick in the Verado's.
I asked the same question somewhere else recently and someone brought up a good point.. I run my jet around 45-5500 rpms.. Cars don't cruise that high.. It costs me an extra $30 to use the Yamaha oil but I don't want to risk it
its very high quality synthetic, is it different, hard to say, good one for the boat shop mechanic.
Other thing to think about most recommend 100-200 hours between changes. i believe my Yam 115 is 200 hours in the manual. I fish a ton and only run about 75 hours a year. I still change it usually once per season. So for only one change its worth the extra cost i would say.