Got a couple of these FORD TOURNEO 2025 MODELs
for the business, but as soon as -37C kicked in full winter mode, all kinds of problems proceeded.

Firstly the ADBLUE nozzle hole would freeze shut,
and the inner funnel tube would be caked with ice.
Making it almost impossible to add fluid.

Next the cold start would be impossible as the batteries would be dead after a couple tries starting.

Coolant levels are normal.
Batteries (1 under seat)
and 1 under hood at back right corner already has
some corrosion buildup.

Engine oil viscosity unknown as these vans are all leased.

Any tips & suggestions how to get these machines running again?

 

First,, it depends on what the lease says. Some take care of all maintenance, you just need to make it available, some place all maintenance on the leasee.
I can;t imagine a business wanting to be responsible for all maintenance.
If it is a common problem, there may be a service bulletin to address the problem.
In that case , the dealership should handle that problem.