Not sure of engine size, but my book of operating instructions says it takes 0.28 litres (half a pint) of good quality multigrade 20/50 or SAE 30 oil.
Change the oil after every 30 hours of use.
If you know of anyone wanting to buy one, mine is now redundant after a recent move to a house with a smaller garden. artspeck at talktalk.net
Art Speck, April 2009