I don't know about the "service" thing. Sometimes I think the only thing being serviced is the customer. My F-225 is 4 years old, has 400 hrs on it and never been back to shop.
Every 100 hrs I change oil filter ($22) oil (Mobil 1 $25 or so) and once a season change the Yamaha 10 micron filter ($20 ?) and lower unit fluid with synthetic (about $15). I own a grease gun ($20) and can grease the fittings etc. The rest of what you pay is labor and profit.
I did replace a couple of t-stats a year ago. One had frozen up (I don't always have access to engine flush). At a "weak moment" I gave in and went to a well known boat/motor dealer. He mis-diagonosed and replaced the water pump, never picked up a torque wrench, or used any anti-sieze.
Experience has taught me the futhur away I am from "service", the better I and my boat are!
by the way, there B-Faithful....Mercury thought so much of the "expensive to service" 225-4 Yamahas, they bought all they could (for years), painted them black and called the Mercurys.
Some would say the're the finest motors Mercury ever put their name on!

:lol:
Now those 4 blade Merc props...WOW !