I don't know about synthetic oil, but I can wave the flag for slick 50.
Have been using it in my 7.4 since the engine was overhauled in 97. When
we did a haul out and tear down last winter, the thing looked brand new.
NO wear anywhere! I change the oil every 150 hours or 3 times a year.

Capt. Frank
La Dolce Vita
Formula 26 PC

Curtis Gassen wrote:

I am a big fan of synenthic oil in my cars, will it hurt to use this in a
2000 7.4L mercruiser? I talked with a mercruiser dealer and they gave me the
standard line to only use their mercruiser oil. also if you can use synethic
can i also put in slick 50 or something similar?

curtis