[Brian in Tucson]

Here in AZ, where old people go home to the north in the summer, it isn't uncommon for gas to go bad in 6 or 7 months. So you and your son should definitely completely change the gas, replace it with fresh premium and a pint of Techron to clean out varnish.

After 8 years, the oil might be okay, but do you really want to chance it? So at the very least, new synthetic oil 5w 30 or 40, and a new filter. Inspect the filter for shrapnel and plastic shiute.
Since you're working with your son, I might even pull the oil pan off for a look see.

Coolant might be okay, but plan to change it soon.

Brake fluid is probably due for a flush.

Inspect the brakes.

The tires are way past their expiration date, 6 years is pushing it.