Pretty much ever since I changed oil in the gearbox the 2-1 downshift has been finicky. Initially attributed it to cooler weather and then to winter riding but with the weather warmed up and the bike coming up to temp faster now it's still occurring and actually more frequently. The problem did not happen once on the factory fill. I used the recommended AGIP Gear MG/S 85W90 oil and filled to bottom of the hole w/ bike level last year when doing the service. All other downshifting is fine, and hardly ever hit false neutral on upshift, clutch lever feels fine.
Is there a better gear oil to be using? 75W90 full synthetic solve this?