Just make sure the oil you use does NOT say "Energy Conserving" in the bottom of the round API ratings label on the back. Mobil 1 15W-50 (aka "Gold Cap") and Shell Rotella T (5W-40 full synth in the blue jug) are very popular car oils for motorcycle use. I am switching to the Rotella T (today in fact) from the Castrol full-synth I had been using. Ran dino oil for the first 2.5K miles.
Will it void a warranty? Dunno. Kawi would have to prove that your choice of oil (or any other mod or self-performed maintenance) was the cause of the damage (US law only). So if your tranny goes tits up and they determine you weren't using JASO approved oil, they may deny the claim. Of course, they've denied claims for all kinds of reasons as documented on here in other threads. Perhaps justifiably or maybe not. Lots depends on whether your dealer will go to bat for you on any warranty claim. Or you may have to lawyer up if you think it's worthwhile.
If you don't want to worry about it, do everything by the book while under warranty. Expensive and perhaps a PITA. You might still get screwed on a warranty claim regardless.