I use my boat 6 months out of the year put about 75 hours on it and change once a year right before winterization.

Change mine at least 2-3 times a season. (50-70hrs.) It's cheap insurance plus it gives me a piece of mind!

The drive oil gets changed 2 times a season also. Once again cheap insurance.;)

change ever 30 hours or 1 once a season which ever is less
Mobile 1 motor oil , and pennzoil synth marine drive lube
check both drive and motor oil after each use

there sure do, i dont know wat they r thinkin but they do

I bet that TooOld changes his every 5-10 years. :D :D

I dont see how you could go that long with a big block, but our 4.3 is at 1500 hours, 1 sinking, valve stem seal finally started to go this year, so its not like it has been unreliable at all.

Fifty hours, (or once a season for us northern boaters) is well within reason. Normal oil change interval on recip aircraft engines is 50 (dino oil), and the turbines are run upwards to 1500 hours or more on their synthetics before changing, and the temps on both types are higher than you will ever see in your boat.
Changing it more often in your boat or car may give you that warm fuzzy, but it really isn't necessary, and in some extreme cases is a waste of money, time, and resources. Their is almost NO chance that oil type, mfg., or cleanliness will be the DIRECT fault of your boat engine failure if you are following either mfg. recommendations, or just plain common sense.

Once a year at winterization 50/60 hour. Last motors had 730 hours when replaced for "mopower" and ran like new 1989/330/454. New 540's will probably get changed twice a year. Already did one with 1.7 hrs when I blew and oil line:mad:

[QUOTE]Originally posted by PhantomChaos
I bet that TooOld changes his every 5-10 years. :D :D [/QUOTE

Ya with 0 hours per year I guess the oil can go a long time :D

I change about every 20-25 hours.....Oil is cheap, engines are not. It comes out dark everytime. In my ski boat it gets it one time per year, but only gets about 30 hours or so a season.

Allan:)