How much oil does a 5.5 hp Honda mower hold?

The manual says 22 ounces (.69 us quarts) for the 5.5 commercial Honda verticle shaft. I have one and the dip stick says it full at 18 ounces? You should be safe at 18 ounces. Ive always been told to not overfill an engine with oil so I don't. Rich's Lawn Service--35 years inn the business!!