Best oil content
G'day
What seems to be the best oil content in fuels for OS engines? I started off with 20% oil a mixture of 50% synthetic oil and 50% castor oil. Now have gone down to 15% oil both agin a 50/50 belnd of castor and synthetic and my engines seem to react extremely well to it. I believe that have gained 100-200 rpm out of the less oil. why would this be happening