Ha, just realized that I've owned my savage for 17yrs runs as good as ever just switch to t6 rotella and I'm noticing my clutch seems not as grabby at full WOT which is how I aways ride 😳  I ride it from 0 to 45/50 in a fast as it will let me . But it seems to have less grab than I remember. Is there any tricks to determine why or if the clutch is slipping? It's grabbing bit it feels like it's slipping at wot. Should I switch back to t4?

Is the T6 you used a new bottle.......and not something that was made several years ago (white bottle)?

There was a short period of time when they increased the amount of Moly in the oil, and several folks had clutch slippage issues.

I would not bother taking the clutch apart if the T4 cures the problem.  Just use the oil that works best for you.