Thank you for looking for the right oil spec.Forgive my ignorance on the subject but I am struggling to actually locate a suitable oil that complies with the specification in the manual. It requires API GL-4, SAE 70W which I believe is very low viscosity.
Using the oil recommendation tool on the manufacturer websites yields further confusion with the following suggestions being made:
While both lubricants are rated at the correct GL-4, neither complies with the 70W viscosity and strangely the Motul recommendation is actually for DCT transmissions (although it says it can be used in some trans-axles).
- Millers TRX Synth 75W https://www.millersoils-shop.co.uk/trx-synth-75w-fully-synthetic-transmission-oil
- Motul Multi DCTF https://www.motul.com/gb/en/products/multi-dctf
While I have no doubt that either oil would work well and that 75W is incredibly similar to 70W, I am very conscious that any deviation from manufacturer specification could result in trouble if my gearbox grenades in the future.
It seems that the Shell Spirax S6 GHME MTF (H for Hyundai) can only be bought directly from Hyundai themselves and there is next to no information about it. Even Shell do not seem to offer any other 70W for general sale.
I see Honda MTF3 oil is compatible too.
https://www.torque-gt.co.uk/genuine-honda-mtf-3-gearbox-oil-1l.html