Bass And Walleye Boats had a great article covering that issue last Spring, I believe. If you can locate a copy of that issue, it is worth thr read.

Basically, as long as the oil is TCW3, and lists that it meets or exceeds the warranties of all the engine builders, the oil will perform well.

I use a special oil for my Opti Max recommended and blended for the outboard by Quicksliver/Mercury, and figure it to be good insurance.