Well I've got all of one afternoon of milling experience, but its amazing how much you learn even after just a few hours. I've got the same mill, with an MS-660 and I installed the aux. oiler. The reason I did, was I wasn't to sure how well the oiler on the saw was working, as I only just bought it (used) so I wanted to be safe with the 36" bar I was using. A couple of things I can mention about the oiler, is you have to be pretty carefull about installing it as when drilling the hole to mount the injector, the instrutions say that it should protrude roughly .040" into the chain groove. If you locate it to far into the groove , you may interfere with the chain, and also tightening the nut might crimp the groove and pinch the chain. You just have to take a little care in locating the center of the hole is all, otherwise its not hard to drill the hole really. I used a center punch and calipers to assist with this. Also, if you are not using (not sure of the corret name ) the handle assist which mounts over the tip of the bar, Granberg says to locate the injector fitting 6" from the tip, that way you are not to far in towards the center of the bar, which leaves more usable cutting area. I didn't find the oiler to get in the way at all, though I was only milling 22" diameter logs. On larger logs Granberg says to just remove the oiler and rely on the saw to oil the chain. In closing I like the idea of using the aux. oiler, worse case, its a backup to the saws oiler, in case it gets clogged, and could save your bar and chain from overheating. Good luck with your Christmas present, you're gonna love milling, I think I'm addicted after one session.