Anyone have an idea of the range of Mix Ratios Used in Old and New 2 Cycle Engines running today? I have Citgo oil bottle showing the ratios from 16:1 to 50:1, and I know the synthetic oils run at 100:1. 50:1 seems to be the standard ratio for newer engines, while 16:1 is might be a thing of the passed since the engines are so old and the oil is better today. The next lowest ratio I have is an email from Stihl saying if you don't use their brand oil to use 25:1, rather than 50:1 . Echo claims you can use 50:1 in all engines using their brand oil.