oil change is easy. Buy an extractor - something like this
http://www.amazon.com/Mityvac-7400-Lite ... 476&sr=1-1 Don't buy a cheap electric pump... they don't work
Run the boat for 10 minutes to heat up the oil.
I put the extractor hose into the oil drain hose and suck it out. In the 5.7 model I sucked the oil out through the dipstick. If I don't get all the oil out. I will add a quart and suck that out too. It takes about 20 min to get it all out.
Remove the oil filter - I usually put a plastic bag around the filter so it it catches the oil. I replace the filter with a Napa gold 1069. If the !@#$ wont come off, I have removed the remote filter bracket (leaving all the hoses attached) and taken a large pipe wrench to the filter (work on it in the storage locker).
Put oil back into the engine and run it again... check the oil level.