Out here in Hawaii it'll take me a month or more to do 500 miles. Is there also some sort of timeframe that the gear oil change should be done? Also how difficult is it ot change the oil yourself? I have never done anything like that, but if it's not too difficult I can take it down to the hobby shop and do it.

 

It's very simple. You unbolt the differential cover and the oil seeps out the bottom. Re-tighten the bolts around the cover and fill with oil.