Bonjour Hans,
Personally, I have never dared to put any thread locker on my little engines, considering the small sizes of the different screws, nuts and bolts and their possible fragility when unscrewing.
I wish you will find this alkylate type of gasoline, it is really great, before I used to put 4 drops of 2 stoke oil in the tanks with SP98. I can see it on Amazon :
Amazon.fr: essence alkylate 2 temps
In all the cases, never more than 4% oil in your mixture otherwise the engine spits it out !
I have also tried "Essence F" but have not been convinced.