Thanks for advice freebird.
I put a bit of Moreys oil stabiliser in....I think it helped.
I mowed a friends lawn today with it, then 80% though the job I noticed oil running down side of mower base, maybe from valve cover, but not that......
I told my friend stripes may appear on her lawn later in the week, but she didn't care.
Filled the oil and mowed my lawn, it didn't leak, but I didn't run it at full throttle like on my friends lawn .
Anyway it looks like it is OK.... for some more small jobs....
I'll upload a pic of the lawn.........
speedy