[jupp0r]

Sure, here are some postconditions for ChangeOil():

- engine has appropriate amount of oil in it

- oil filter in place

- drain plug torqued correctly

- dip stick present

- oil cap on

No matter what the outcome of the operation (ie error paths or happy path), ChangeOil promises to return with the car in a state that fulfills those conditions.

In order to do that, some preconditions need to be fulfilled too:

- car has some amount if oil in engine

- car is able to start

- no major noises

[AgentOrange1234]

Yes and frame conditions… Wheels should still where they were, nothing stolen from the glovebox, no bodies added to the trunk, brake lines uncut, etc.