The worst thing you can do as a owner is to let the maintenance cost
eat up all your gas money, and you ended up keeping a hangar queen for
the next owner, one with a rusty engine no less. There's nothing
sadder than that.

A far worse injustice is leveled on many airplanes. Namely, the owner
cannot really afford the plane so they choose to buy gas to fly around
and then skimp on the maintenance. He/she then demands a ridiculous
selling price for their run out dog when the HAVE to sell.

In either case, if you have to ask, you likely cannot afford it. Those
using spreadsheets and trying to calculate this down to the dime may
want to consider that airplanes don't require cash according to a
schedule. If you don't have $5k - $10k laying around at all times (and
not in the form of a loan), you are going to have a tough time making
ownership work out.

Airplane ownership is NOT like a car or boat. You are not an owner, but
a temporary steward of an increasingly rare object. I consider it my
responsibility to keep an airplane in good shape (repairs, upgrades,
etc.). Many people (especially in my home America) have a hard time with
this concept. They are accustomed to buying things and then throwing
them away when they become old or inconvenient.

Good luck,
Mike