pro user generator fuel mix

[kev b]

Can anyone tell me what strength petrol/oil mix to use in a Pro User G850 generator ? It has a measure inside the fuel tank cap,is this the correct amount of oil for a full tank?

[mrsxllifts]

The mix is 50:1 but not sure if the cap is for mixing. Ours died at Le Mans a few years ago so left for the locals!