Okay, i have serviced the 3720 so it should be the same. First, find a bucket or pan, and crawl under the middle of the tractor. There are actually 2 oil drains. Unscrew the one that is closest to you (on both left and right for convenience) and slowly unscrew it. Once oil starts coming out, pull the plug away (so you wont drop it in oil pan.) Once oil is drained out, screw the plug back on top hand tight with a wrench for easy servicing. Next, remove your oil filter. If you have rough hands or good gloves, it should screw right off. If not, put a screw driver through the filter (your throwing it away anyways) and unscrew it. Put a new filter on to hand tight. Next, you will need a funnel. Unscrew the oil cap and insert funnel. Location is kinda hard as the funnel has to be squeezed between tractor and FEL (if you have it on). Then you put in 5 quarts of oil, periodically checking the level. Once it is full, put cap back on. (that's it) :thumbsup::thumbsup: hope this helps. :thumbsup: