Okay, guess I'll come clean...I recently changed the oil in my Sporty to 15W-50 Mobil I...for several reasons...1.) Price $4.99 a quart it was a bargain $$$ wise, and 2) since I change oil every 3,000 miles because of my stop and go daily driver/commute vehicle application, it was just my personal decision to see if I would notice ANY long term effects.
Yes, it is minus the tiny bit of zinc low wear additive...but it still is 100% Synthetic Mobil I not a blend like Syn3...having all the friction modifiers, purity (no ash or unknown ingedients, and performance attributes only 100% Synthetics can provide. Honestly, I could use dino oil if I really wanted to save money as my engine runs cold, oil tank rarely gets over 160 deg F with plugs & pipes indicating a bit rich and I can get off the choke almost immediately after starting..m!
The point is if your bike is not running on the fringe, it will NOT self destruct just because you do a minor change in your oil under these conditions...and for a short time it is in your bike. It is your ride and you decide. I would probably not do it if I were running later model fuel injected bikes, but then I would also not be concerned about the $$$$ nearly as much either.