Synthetic Motor Oil in 4-Stroke Outboards

[Kamalot]

Just wondering if anyone has knowledge Pos/Neg on replacing Petroleum Oil with a Synthetic after Break-In on 4-Stroke Outboards?

Considering this on my 4-Stroke Yamaha's 225 & T8-Kicker.

The Manual calls for 10w-30w (SE,SF,SG,SH,SJ), and I'm considering Amsoil Marine 15w-40w (I called Amsoil and they said it would work just fine). Or another Synthetic Brand in 10w-30w.

Your thoughts!!!

Cory

[boater]

i use mobil 1 in my 4 stroke honda with no problems.

[Hanapa'a Time]

Been running Mobile 1 synthetic(10w-30) in my T8 for over 100hrs. Still change at 30-40 hrs., no problems yet.