labrat

My son and I were lucky enough to be given a pair of about '93 vintage Trek MTBs complete with rigid forks and many problems. I've gone through them and repacked the wheel, bottom bracket, and headset bearings. Relaced one of the wheels with a new rim, replaced a canti brake that was missing parts with a mini-v, spent a fair amount of time getting the shifters to work right again, and just did a lot of general clean up and replacement of the missing little bits. I figured I was done but started thinking about the freehub (Shimano 7 speed). I figure they have very little load when coasting and none when pedaling so they really shouldn't need attention unless they act up. Is this right or should I pull them apart and shoot a little oil at them? I've never serviced a freehub (I know - if I can relace a rim on a wheel a freehub should be cake), so is this the time when I ought to learn?

Thanks for any input,
Labrat