What's the service intervals for gearbox oil and diff oil?

The diff is inside the gearbox therefore using the same oil. Use a clean/pristine bucket when draining the old oil, makes things easier to spot brass colour particles and how much there is

 

Intervals are every 18 months or 18750 miles (whichever comes soonest)
https://www.renault.com.my/storage/...S_Periodic_Maintenance_Service-1603198170.pdf

 

Must be something wrong with that maintenance schedule. Changing gearbox oil every 18 months/30.000 km can't be correct.

 

Some interesting reading regarding PK4 box issues and merits or otherwise of more frequent oil changes.
If you track a mapped RS and can do your own transmission oil changes, $100 every 2 years or so is pretty cheap insurance.

https://www.renaultsportclub.co.uk/...k4-gearbox-bearing-issues-on-my-megane-mk4-rs

 

Totally agree. I change the gearbox oil every engine oil change. We are talking about 50GBP extra and peace in our minds.