Can I leaave my coolant unchanged since trucked is parked and not used

Good day. Writing from Norway with truck parked in West Arica. I will be
grateful to get your views on my truck. I have a Toyota sequoia 2008 with
odometre reading of 97,000 miles. Coolant is supposed to be changed when
truck is 10 years or has reached 100,000 miles. In august 2018  it will be 10
years with 97,000 miles. I am currently out of the country and will not be back
in 2020 August by which time truck will be 12 yrs. Truck is parked in my
garage -not used.

1. Can it be parked in the garage until I return in 2020 and have it changed?

2. if it can be parked until my return can it be started every 6months with the
old coolant?

There is no insurance and roadworthy cert. on the truck, the reason why I
dont want the truck out o my garage. It is prked with new oil and on jack
stands without tires toching garage floor. there is also enough ventilation as
garage door is partally opened when occupants are at home.
Hope to hear from you.