71 to 1 ???

[2dogs]

I can only say I have been using Opti 2 for many years without any problems. I just ran out (I buy the gallon size) so I mixed up a 6 gallon can of Blendzol. Both oils have served me well.

 

[fordf150]

oil is cheap. rebuilding a motor is not. 32-40:1 would be my choice no matter the claims of the oil manufacturer

 

[Little Al]

Basically, yes. All the smaller containers here are 5 litres=1 Imperial gallon. It is also why we never call a bottle of Rum here a 'fifth', as 750ml is a fifth of a US gallon. Using metric makes is very easy to mix ratios.

This leads me to a different point. We are now seeing more and more strato chainsaws. And we are hearing from the field that these saws are using less fuel for the same amount of work. Husqvarna and Stihl say it can be as much as a 20% improvement in fuel economy. And we're also hearing the same for M-Tronic and AT saws. This is all fine and dandy. Well, except we are also seeing(at least in Europe, according to some techs I know) a lot of young saws(550's and 261's mainly, and recently a few 365XT's) die early deaths due to bearing failures. This is purely anecdotal, but I suspect the strato charging may be having more of an effect than simply better fuel economy. After all, if you are seeing a 20% less fuel used per tank, that also means you are seeing 20% less oil usage. 50:1 is already 2% fuel to oil ratio, vs 3% at 32:1 or 2.5% at 40:1. But a strato that gets 20% more fuel economy with a 50:1 mix is likely running close to 60:1 as far as the crank bearings are concerned if you consider the fuel/rpm or fuel/run time ratio vs the previous generation. As I recall, plenty of saws running at 32:1 seized as well. I'm not sure it's a great idea to make it any easier to lean out a saw - not at today's prices. Just a thought...

There have been some fatalities in the commercial side of logging in our area, more so Stihl but also Husky, this could be down to the possibility that there are more Stihl"s in use however we are running the works saws (Husky"s ) at what works out at 38/1 it"s just a large quantity mix that comes out at that, so far no problems also the limiters are gone & mix is set (properly) not to suit the enviro bods, as stated before I"m of the old school so rightly or wrongly I run 32/1 in my kit & keep on top of the mixture setting"s & close on 45 years have never had a saw fail through an oil/fuel ratio problem

 

[Ronaldo]

I can only say I have been using Opti 2 for many years without any problems. I just ran out (I buy the gallon size) so I mixed up a 6 gallon can of Blendzol. Both oils have served me well.

What rate do you mix the Opti 2, 2dogs?

 

[Chris-PA]

Basically, yes. All the smaller containers here are 5 litres=1 Imperial gallon. It is also why we never call a bottle of Rum here a 'fifth', as 750ml is a fifth of a US gallon. Using metric makes is very easy to mix ratios.

This leads me to a different point. We are now seeing more and more strato chainsaws. And we are hearing from the field that these saws are using less fuel for the same amount of work. Husqvarna and Stihl say it can be as much as a 20% improvement in fuel economy. And we're also hearing the same for M-Tronic and AT saws. This is all fine and dandy. Well, except we are also seeing(at least in Europe, according to some techs I know) a lot of young saws(550's and 261's mainly, and recently a few 365XT's) die early deaths due to bearing failures. This is purely anecdotal, but I suspect the strato charging may be having more of an effect than simply better fuel economy. After all, if you are seeing a 20% less fuel used per tank, that also means you are seeing 20% less oil usage. 50:1 is already 2% fuel to oil ratio, vs 3% at 32:1 or 2.5% at 40:1. But a strato that gets 20% more fuel economy with a 50:1 mix is likely running close to 60:1 as far as the crank bearings are concerned if you consider the fuel/rpm or fuel/run time ratio vs the previous generation. As I recall, plenty of saws running at 32:1 seized as well. I'm not sure it's a great idea to make it any easier to lean out a saw - not at today's prices. Just a thought...

I've gone round and round on this issue of oil in a strato. There should be 20% (in this example) less oil in the case at any given time. However, the mix ratio is still the same (say 50:1). Also, not all the all the air moves through the case, so if you consider what is in the case as a vapor or mist of air/fuel/oil, then there is maybe 50% less air in there (i.e. a higher oil concentration).

From the point of view of the bearings, they are not in the main air flow path through the case, rather they are a pocket off to the side. I suspect they get coated with a mist of fuel mix which condenses out and sticks there, and I kind of doubt that it is flowing at the rate that mix flows through the case. Alternatively you could not have any kind of pool of oil on the spinning bearing as it would be flung back off. So my WAG would be that in terms of bearings what matters most is oil ratio - and since 50:1 and stratos have sort of come in at the same time it will be hard to tell which (if either) might be responsible if there are more bearing failures.