I just love these oil mix threads...seems like this pops up now and then.
I visit a gardening forum now and then, and some of the same questions pop up regularly...finally the administrators put up a page of FAQ's to make it easy for newbies that may not have seen some of the old threads. Even that engendered some controversy...if a newbie shows up looking for advice on planting sweet corn and gets his info right away, maybe he won't participate after that. In the end we all agreed that he probably wouldn't anyway.
Here are the general points we all tend to agree on, regarding oil:
Those old 16:1, 20:1, 24/25:1, and sometimes even 32:1 recommendations were for older saws with looser tolerances, and more importantly, older oils with looser spec's The only two-strokes made any more that really want the higher oil ratios are the really low=end stuff like the little Techumseh power unit on mini-tillers and a few ice augers.
If you choose modern, name-brand, high-test oils, oils labeled "service TC" (the lowest spec) or better yet, "Jaso FC", and "ISO L-EGD" you can pretty much trust it in any air-cooled product. I won't advise running an old saw from the 50's at 40:1, but I run everything I own at 32:1 without trouble...including a 1949 McUlloch 3-25. At 32:1 I don't have trouble with low plug life, port fouling and ring sticking, so it seems OK for the modern stuff, and the antiques seem to tolerate it just fine. That allows me to have one can of mixed gas.
I was at a home improvement store recently and saw a syringe-like doodad for sale allowing the user to measure oil precisely for as little as a pint of gas. 1 TBSP oil is 32:1 in a pint of gas! Seems like too much fooling around for me!
