Mower oil?

[motorbiking]

I haven't changed the oil in my mower (brigs n Stratton 4.2hp) for probably 10 years.. I have lots of unused engine oil mostly for motorbikes ranging from synthetic to semi synthetic. I'm assuming this will be perfectly fine in my mower and it will be grateful for clean anything?

 

[conny]

My oil is EFCO mower oil. Only thing it says on the bottle is SAE 30 for use in 4 stroke engines.

 

[Burnerman]

A straight 30 oil is the usual recommendation for air cooled engines as it's more stable when hot.
Feel free to use a 10/40 semi synthetic lube if you want.
John