Hi,
Am not a Diesel man, but some of your info does not seem right according to the info I have,
The Haynes manual states changing the gearbox oil every 40,000 miles or 4 years.
Not sure why you are changing to 0W-40 oil, particularly a thinner one, again seems 5W-30 is the correct grade ?
Don't forget to change the Key batteries and fuel filter.