I'm used to paying $50-$80 for my OS FPs, Tower and Thunder Tiger 2 strokes but just plonked down $200 for a Saito FA .62a. I'm not about to risk my $200 on fuel manufacturers who market their fuels only as "containing the finest ingredients" but then tell you it's a "secret" formula.

If the manufacturer recommends 20% oil, then that's what I run in it. If I can't find a commercially available fuel I supplement an 18% or 17% fuel with enough Klotz or castor to bump it up to the recommended brew.

The fact that you have to wipe off the residue from your model should serve as comfort you're only wiping off oil, not metal.