On 18 Dec, 22:23, geoff wrote:

It says to use 10/30 oil, I've got some SAE 20 fork oil lying around,
should that be OK ?

No, no heat resistance and it will carbon up in no time. As sticky
rings are a big problem for littl engine failures, that's bad.

Use convenient random car (petrol) engine oil. Approximating 10/30 is
good, but it's not going to complain too loudly if it's 10/40.