Dazed's oil/solvent mix from Eagle Research.
It may be possible to get a higher concentration, but there are reports of it crashing. I also had some pre-made crystalize after using about 2/3 of a 10 ml vial. I had to heat it everytime I got ready to use it and I was trying to avoid having that happen with what I made.
Yes it is pain free at 100 mg/ml