It's only allowed for PFA aircraft, not for CofA. The filling points must be appropriately labelled. I suspect you'll need the PFA to agree to it for your type, but I don't know how this works.
Once you have more than a certain percentage of MoGas in your tank (is it 80%? I can't remember) you're not allowed above 6000', and you're not allowed to fly with a tank temperature of over 25 degrees C.
Also, make sure you have a reliable source of MoGas! My Europa had a serious problem of black bits collecting in the fuel filters. We couldn't figure out what it was. Then the petrol station next to the airfield closed. Although the black bits haven't completely gone, there are far fewer of them now - the local petrol station was obviously supplying contaminated fuel.
The PFA are the people to speak to for definitive answers.
FFF
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