40 minutes down to 9 on a VF-2 sounds like you were touching off every tool in the carousel and now you're not. That's not a gimmick, that's just math. But $600 for the whole machine and you're asking if the repeatability drifts after a few hundred swaps, so you already know the answer is probably yeah, a little. Question is whether a couple tenths matters on the parts you're running, and if it doesn't, why are you even asking us? Buy the holders, check one with an indicator every month, and move on.

Man, I always brushed off the oil weight thing as internet nitpicking. I figured oil is oil and the manual just picks whatever helps them hit a number. Then I watched a buddy's mpg drop about 2 after his shop put 5W-30 in a car spec'd for 0W-20, and it went right back after the next change. Your numbers are pretty tight too, same route, same station, 2.4 mpg is not nothing over 6 months. The age thing is real but it wouldn't hit that fast unless something else changed. If I were you I'd go back to 0W-20 for one round and see if it climbs back. That notebook is doing more than most people's guessing.