40-1 vs. 50-1 ???

[Yoopermike]

A saw running 50:1 runs cooler than a saw running 40:1 as the fuel itself helps cool the saw.

 

[chuckwood]

You're going to get all sorts of opinions on the matter.

End of the day, as long as you're using quality mix and not letting it sit around for ages, I think you're fine with either 40 or 50 to 1. I personally use 40 to 1 in everything simply because its easier to remember for all of my saws and equipment, and its one of those cases where its just "worked for me" always.

I mix everything 40 to 1 because my brush cutters and Ryobi weed eaters, except for one Husky brush cutter, are all labeled 40:1 mix. Been using 40:1 high octane 100% gas mix in chain saw milling which really puts serious stress on saws. So far, no problems. I am switching over to full synthetic instead of synthetic blends. I run milling saws a bit rich, fearing heat problems more than carbon build up.

 

[weimedog]

I'm far from an expert, but my educated guess would be 2-stroke oil has more [BTUs]... however all the tests/reports seem to attribute the increase in HP to better ring seal and thus higher compression. I would also believe more oil would increase the octane of gasoline (i.e., harder to ignite oil than fuel), but that's likely insignificant.

Castor bean oil is still sold, like Maxima 927. Some old timers and racers swear by it. My understanding is it had/has some better lubrication properties, but they come at a cost... separation from fuel and deposit control. Now how does it compare to today's semi-synthetic and synthetic oils from a lubrication stand-point.... I don't know. Newer oils defiantly have better deposit control and less likely to separate.

Now we are getting somewhere. Not all the reports attribute all the power gains to better seal but many do and that is one of the benefits to adding more oil. More BTU's with the "mix" has an effect as well but really how do you quantify that? There is a measurable increase in temps and part of the reason why is the more BTU's released and part might be the operating compression. But how would you test and measure the percentage of power gains attributed to those different attributes? Often time "reports" are observations and then best guess rationalizations to what they observed. Add marketing to that and they are there to make a point. I would say the higher oil ratio's give a multitude of small advantages that include better sealing of the rings and more BTU's as well. There are others... Octane is more about stability and allows a tuner to get closer to that pre-ignition edge. The beauty of products like Bel-Ray H1R and others are the fact you can mix those higher ratio's without a significant increase in residue in the exhaust. Bean oil does burn dirty but has a unique smell that many racers grow to appreciate as one of the back ground things you remember from the racing world. Klotz used to sell a Caster Oil along with a few other very targeted product for situations. Actually worth a visit to their website if it's still around. Of course 4-Strokes made that go away....Racers are all about empirical vs. theoretical. They live in a world where success is defined by simple numbers. Often time the best real information is gathered there. But this is progress....

(We can discuss the lubrication side another time)