What is likely to be a car equivalent for the expensive 'Mountfield' stuff?
Just get anything that has similar viscosity etc (the 20W/10 numbers - get them from the mountfield bottle). In reality though, I wouldn't have thought a lawnmower engine is unduly stressed, so as long as it's got some oil, it shouldn't matter too much what it is...
The bottle didnt have it on but the power of the internet has given 5W30 Synthetic - not much cheaper!
5w30 synthetic? my motor runs on 5w40 synthetic! Its a lawnmower - its not a sophisticated engine unless its a commercial unit so i'd batter anything you have in it...
Consider it done!
nb. my advice is not legally binding 🙂
Synthetic is just longer lasting and slightly cleaner than mineral.
Lawnmowers dont realy get very stressed, you could probably even run it on single rather than multigrade if you wanted.
Pop into halfords and just get the cheepest 5w30 you can get, synthetic oil could probably outlive the average lawnmower!