I didn't personally, but the seller said he'd just put fresh oil in it (and it looked super-clean). The elf stuff is totally clear and super-thin--almost like water, I think it is a bit different than most gearbox oils and the clutch works really nicely with it. The montesa guru guy at Overland at white rose insisted that the clutch worked way better with the elf stuff than anything else (he does sell elf oil, so a bit of a chicken and egg question). I really didn't expect the oil change to do much for the clutch, I've never noted a big difference with oil on any other bike, but it was night-and-day different with just the oil change on the 'tessa. For my uses it'll be less than $40/yr for the good oil. If I were riding every day and changing oil weekly maybe it'd be different, but for now I don't think its worth trying something else for me. I also read a zillion threads on trialscentral where folks struggled with clutches and almost universally their problems went away when they used the elf oil. There is some other oil (might be the silkolne) that's about half the cost that they say works somewhat ok at first, but then gets draggy much more quickly with use, necessitating more-frequent changes so probably a wash there.
I don't know if the 314 has the same clutch, it might. The 315 has a weird clutch stack that has some cork plates and some paper plates.
I remember that log, congrats!
BTW I'm switching jobs and will hopefully have more time to ride with the new gig, but its in Tampa so I'll miss out on next year's D6 events. On the bright side there's a trials course within an hour of Tampa that's in a public riding area so I'll have a place to play (few rocks, but logs and surprisingly steep hills).