I ran a couple of gallons of gasoline using 32:1 Penzoil 2-cycle oil through my Brison 5.8 and the compression was so good at that time that I switched to Klotz KL-300 synthetic at 50:1. I've been very satisfied with the results. I don't remember having to change the needle valve settings. I fly a real variety of gassers including a Brison 6.4 and the Brison 5.8 is absolutely one of the best.

Ken