NewMan > writes:

> At the risk of getting into semantics....
>
> The Imerial Gallon is 4 quarts also! However the Imperial Quart is 40
> fl. oz. - whereas the American Quart is 32 fl. oz.
>
> That makes an Imperial Gallon 160 fl. oz or 4.54 litres, and a US
> Gallon 128 fl. oz. or 3.78 litres.
>
> Thank GOD that a fl. oz. is the same in both systems.

Are you sure about that? According the numbers you used above, a US
ounce is 29.53125 ml, while the Imperial ounce is 28.375 ml.

This is reasonably consistent with Wikipedia, which states a US fluid
ounce is 29.5735295625 ml, while the Imperial ounce is 28.4130625. ml.