What gearbox oil, how much, and how often to change it?

• Oil: 75W-90 gear oil (or 80W-90)
• Volume: about 80 ml — up to the check bolt
• Interval: per the manual every 40 hours, first change at about 5 hours

If you ride through water and the breather isn't raised, change it more often — water emulsion happens.

Torques: drain bolt 15 N·m, check bolt and filler plug 5 N·m.

Stark videos: MX 1.2 — https://youtu.be/MzsXAV4Ee1E, MX — https://youtu.be/24lAXWuuTGI