They were very ok with just about anything. I'm not sure what my mechanic is using. I would take any recommendations.
Reason I asked; about a year ago my Bud (Skunk 124HC / DD7 / Scorpion / Solid Sprocket / Hayden Tensioner) was on the speaker with Barnett, trying to get the (exact same) issue resolved. Barnett did not hesitate to send another Pack, and said "a Quart of ATF nothing else", also recommended leaving out the Damper Spring / Seat ... After following the directions to a T, I asked about the Sqweeking 15k mi. later, "most all of it's gone, 'still does it once in a great while"...
Since Barnett is changing their recommendations to "just about anything" from "1 Qt of ATF" I was just curious?? Maybe Barnett has done some design / material changes??
I'm a fan of the Formula+, but I'm running a Comp, and a different set-up...
IMHO the real bogie with the Scorpion is the CVO Hydraulic Clutch, lack of adjustment, not the (higher) HP/TQ... the cable clutch folks don't talk about the sqweek much??
Keep us Posted

PS YorktownCVO, sorry about getting away from your OP... The GM at my Dealer (a real hands on type guy, not your typical GM) when asked several years ago; " I like Synthetic in the Motor and Transmission, not in the Primary"