Noticed mine was low the other day. How do you fill it up? No funny answers!!! BTW, I had been thrashing the nuts off it the other day and when I changed down, whilst braking, there appeared to be a whinning noise. This has never happened again since and when I say my oil is low, I simply mean it is below the minimum but still on the stick. It was serviced by the dealer who I thought would have noticed that it was low unless it has leaked since!

 

go to Halfrauds and buy an orange funnel with flexi centre section, about 1/2 m long in total. (£3.49)
buy 75W90 gearbox/drivetrain oil (I use Syntrax and it seems pretty good)
put funnel into hole left by removing dipstick and pour in oil.
total amount to fill from empty is approx 4litres.
I dont know a single person who hasnt overfilled it when topping up the level so dont worry about that.
refit dipstick and drive off happy
whinning could be power steering pump fluid level also needs topping up, check this before getting worried.