I've got a 2008 Yamaha VMAX 150hp and have run it pretty hard for the last year, plus the guy I bought it from had run it for about 2 years (pretty lightly) and never had any maintenance done on it.

 

 

What kind of periodic maintenance is required to keep things running at top notch? How often should various parts be changed? (Ex: Spark Plugs, lines, filters [if there are any], fluids....) 

You probably don't need to winterize your engine in LA.  Up north, if the boat is not going to be used in the winter months I get mine winterized, and serviced.  Winterizing includes flushing the cooling system with an antifreeze solution.  Prevents damage caused when ice forms in water in the cooling passages.  I also have the lube in the lower unit changed.  They inspect the old lube for things which should not be there such as water and metal particles.  If all is good, the lower unit gets refilled with fresh oil.

 

They change the fuel filter, and lube all the pivot points on the motor.  They also inspect the spark plugs.  They also treat the fuel.  The fuel treatment may not be necessary since I use Stabil Marine every time I fuel up.

 

They run the engine and "fog" it, which coats all the internals with a rust preventive.  Again, that might not be necessary if you run your motor year round, and it does not sit unused for extended periods of time.

 

As the saying goes, an ounce of prevention is worth a pound of cure.

If it were mine I would be changing the water pump impeller. Three years is about all I care to run one. I also change my lower unit lube every year. That also gives you a chance to make sure you haven't developed a leak.

Plugs on oil injected motors like yours should be good for about 2 years. Impeller should be replaced around the same time too. Living down there where you can use your boat 12 months out of the year, you should drain and fill your lower unit every 6 months tops. You can inspect it for water leaks then by the color of the oil, and check for any excessive wear (excessive metal filings in your lube). If you have a water separator, check that every few months and you should be good to go! 

Plugs on oil injected motors like yours should be good for about 2 years. Impeller should be replaced around the same time too. Living down there where you can use your boat 12 months out of the year, you should drain and fill your lower unit every 6 months tops. You can inspect it for water leaks then by the color of the oil, and check for any excessive wear (excessive metal filings in your lube). If you have a water separator, check that every few months and you should be good to go! 

 

Exactly what I was looking for. Thanks!