I started mixing my own fuel a few months back. I use an oil mixture of 8% Klotz Synthetic and 2% Klotz Castor,for a total of 10% oil, with oustanding results. I've put 3 gallons of my home brew through my OS 18TM,and it has treated me every bit as good as the O'Donnell 30% I used to use. Several people at my local track have started using my fuel and I get compliments all of the time.