See also:

Checking the engine oil
Engine oil is essential to the performance and service of the engine. It is suggested that you check the oil level at least once a week in normal use and more often if you are on a trip or driving ...

Changing the engine oil and filter
...

Vapor Hose and Fuel Filler Cap
The vapor hose and fuel filler cap should be inspected at those intervals specified in the maintenance schedule. Make sure that a new vapor hose or fuel filler cap is correctly replaced. ...