And it’s your car in any case!
They probably just don’t do it now in the large drums/pumps. Just the 0W-20
The irony was at the first service in 2019, I mentioned that the print out said 5W-30, when I ‘thought’ it should be 0W-20, and was told not in the UK, we use 5W-30. I asked would it have it had 0w-20 in the factory fill just emptied, and was told no, it would have been shipped to the UK with 5w-30 in it 
Who knows? It’s an easy trade to gas light people with quick answers. Like the building trade etc.
Dealerships are often very impersonal, conveyor belt places. Not necessarily a knock on the particular place, just the model in general.
The motor trade make stuff up, it’s practically obligatory. They’ll do it when you know they’re doing it, and when they know you know they’re doing it.
I always take my own oil. Usually Millers, EE performance or Trident C3 5W-30,
I also used Castrol 5w 30 A5 engine oil and Castrol GL4 Multivehicle gearbox oil.
HOw do you find the gearbox oil, compared to the OEM fill?
Do you use your own oil at a dealership, or at a local guy?
Didn’t notice any difference with gear oil. 1st to 2nd was slightly stiff with OEM until a few mins and Castrol similar. Nothing to be concerned about. Friend of mine has a pump to refill.
You called?
Magnatec - Semi-Synth
EDGE - Fully synth
NA/NB - 10w/40 A/B Mag
NC - 5w/30 A5 Mag
ND - 5w/30 A5 Mag
Of course, cars that track or have boost will benefit from a higher “hot” number (10w/60, 5w/40).
Dealer. EMG, Cambridge. They don’t seem to mind. It’s a multi franchise workshop, I’ve never enquired as to what they use.
Thanks for that, reassuring to know the make up of each oil.
I never thought of doing that. Cheers. Even if I get 5L of the Mazda 5w-30, they couldn’t have an issue with that.