Oil change 4.3 mercruiset

[Hawkeye50]

how often should I change oil on my mercruiser if I troll with main motor?

[pete277]

Every 100 hrs usually 

[Josh A]

I usually do every 50 on my mercruiser.  That oil gets used pretty quickly especially if trolling/idol  

[guffins fisherman]

I would recommend 50-60 hours if you are really concerned about the longevity of your motor.  I would also recommend straight 30, or 40 weight oils. They are considered industrial weight oils and still have zinc in them.