Up down 3000km max on some SS1000 that I run in the past all with oil cooler beneath water radiatorWhat's the longest miles you've ever ran an oil?
Doubt the chain adjustment has much if any affect. I've never seen any difference in shifting after adjusting a loose chain back to proper slack.
today I change every 1500 on a small scooter I run because no oil filter and 800ml amount and on Tenere 700 every 2000 because I run on dirt roads (Motul 7100 10W60) otherwise if I not go to off road again 3000
For gearbox and smooth gearshifts mostly is the chain, never see a better gear shift because I change the oil from one brand to the other
Even on Honda that have tough gearboxes