That model Ranger does, indeed, have what’s called a variable-voltage or `smart’ alternator. The idea is that when the car’s main battery is fully charged, the alternator reduces its workload to save fuel. But the reality is that the system doesn’t always recognise that accessories (like a second battery) have been fitted to the car. If that happens, the alternator doesn’t always make enough power to keep accessories like that second battery system fully charged. Which means that suddenly, your car-fridge won’t run overnight.

The good news is that this smart function is purely electronically controlled, and a Ford dealer can disable it for you, returning the alternator to conventional operation.

If you talk to automatic transmission specialists, you’ll soon be told that it’s impossible to over-cool such a gearbox. An aftermarket transmission cooler is designed to work in conjunction with the vehicle’s standard transmission cooling system, so disabling the standard cooler is probably not a great idea.

The problem with coolant entering the transmission is not an unknown one with some Ford (and other manufacturer’s) models and occurs when the standard cooler fails, allowing coolant into the gearbox and destroying the electronics and the gearbox hardware in short order. Unfortunately, this is a design thing rather than a maintenance issue, so the best thing you can do is service the vehicle regularly and make sure that the coolant is changed regularly. Even then, however, swarf from the production process (according to one theory at least) has been known to circulate through the radiator and cause damage to the piping that forms the transmission cooler. A radiator clean and flush might help stave off this process.

If the manufacturer of the aftermarket cooler you’ve fitted can guarantee that the unit will cool at least as effectively as the standard unit on the Ranger, then you might consider disconnecting the standard cooler. Even so, you’d be wise to keep an eye on transmission temperatures, particularly if you tow anything or travel at high speed in high ambient temperatures.

Normally my advice would be to buy the newest car with the lowest kilometres and in the best condition. In this case that would be the Triton, which would also comes with what remains of the factory warranty, but on all other counts I would go with the Ranger. The Ranger appears to be in good condition, the kilometres are low for the year, and the service history is just what you want.