20 or 25:1 was the old style ratio when the oil was a mineral oil like Castrol Super TT - remember that ? I used to run Castrol R30 in my little MX bikes (YZ80's), at about 30:1, it was a vegetable oil and smelled just like methanol when you were riding !!
The ratios that Marty is talking about are for fully-synthetic two-stroke oils, these are way better than the older mineral-based oils, and can safely run at 40 and 50:1 ratios........I remember back in the 80's, when Bel-Ray first released a synthetic 2-stroke oil, recommended at 50:1, we all laughed and swore never to use it......"how could that shit work at 50:1 ???..."
