Definitely good idea to check the lower unit. Its just you don't need or even want to replace it more frequently than recommended by the manufacturer. Pete's description of what they do at his marina sounds exactlty like my local Honda tech was doing.

Now we all know how to winterize on our own, right?

It is the easiest part. Unscrew the little bolt, drain it, then screw in the hose and pump it in.

Joe G: do you have a recommended schedule for changing the oil in the lower unit? Also, I thought you needed a special pump / attachment to pump in the new gear oil. After the 20-hr. service, my manual says I don't need to replace (but should still check) the lower unit oil until 200 hours. Whats your experience? -Eric

I have had a 1993 15 HP Johnson for the past few years. I just make sure I change the lower unit oil before there is a frost. I tell the guy at West Marine what type motor and he gave me the lube and pump for it. Very easy to do

Eric,
I appreciate all the info. I've never done it to my 4 stroke and it sounds like we have the identical year and model.

Likewise Joe. I think I'll look into getting what I need to change the oil in the lower unit this year. I was going to check it, but changing it can't hurt.

-Eric