Gear Oil - applies to all Scooter

[wke002]

Hi All, 2 months old ADV350, still keeping my Vario160 (same engne as ADV160 ) to commute to work.

had a honda spacy 108, xmax 250, adv150 and now adv350 n vario 160. many of us discuss about engine oil, for gear oil, many or even manufacturer recommend engine oil 10-30 same viscocity as 80-90, i wud not use 10-30 MB, and so far my search 80-90 gear oil are minerals, even top oil maker.
to get fully synthetic gear oil is always 75-90, the quest to find if anyone here use 75-90 fully synthetic gear oil and if there are any difference. my brain tells me a fully wud obviously better than mineral 80-90, maybe ?

i perform gear oil and engine oil (honda fully synthetic) change every 3-4k km, but would love to try out fully 75-90, that is if it can be used on scooter gear.

Cheers.