I feel foolish, however - I managed to place about a gallon of gasoline in my hydraulic resviour on my lawn mower and have ran it about 10 minutes. It has been suggested that I drain the resviour/replace the filter and add more hydraulic oil - run it for a short while and repeat the procedure thus replacing the diluted oil - anyone have any thoughts on this

>moved from Forum Help to Lawn & Garden<

It seems like very sound advice:

Flushing Hydraulic Systems (http://www.insidersecretstohydraulics.com/flushing-hydraulics.html)

Yes it does, be prepared to have at least 3 new filters

Yes, you need to repeatedly flush the system to prevent the dilution of fluid leading to premature failure and/or damage to components.