40-1 vs. 50-1 ???

[CTYank]

Been running 50:1 since it was available (around '80?) in all 2-strokes, from 22 cc Echo trimmer to a variety of saws. All look great internally. Chamber/port/screen/muffler deposits are nil. Smoke on starting is nil. Peering inside, I can see oil film.

Some of these units had mfg recommendation of 16:1 with earlier spec oil. It's all in the oil ratio spec, except that the engine has plain bearing(s) AFAIK.

Most mfgs have changed their recommended mix ratio for earlier models over time, as oil formulations have changed. Seems that the major obstacle is folks who can't or won't measure the oil & fuel in the mix- the ones who toss it in the tank (which tank? who cares?) and hope it runs.

And ... good quality mix oil is kinda expensive to be used as mosquito-fogging agent.

 

[KarlP]

Yup..or 43:1 or 44:1 or 41:1 or 50:1 or 42:1...or, well, you get the idea. :msp_biggrin:

Too many guys over-think the oil thing. Use a good synthetic, keep your fuel clean and fresh, and it doesn't really matter a few drops of oil one way or the other.

Definitely 43:1 for me. I don't want to over-think. Math is hard. 3oz per gallon is really easy.

 

[Gologit]

Definitely 43:1 for me. I don't want to over-think. Math is hard. 3oz per gallon is really easy.

Works for me. Anybody got any real numbers on the difference, in fractions or percent of ounces or whatever, of oil in the different mix ratios? I tend to hang right around 45:1 but I might be off a little either way, too, depending on how much of a hurry I'm in and how much I dribble down the side of the gas can. My saws run fine and seem to last quite awhile. I'm not trying to start a fight and I'm not saying that absolute accuracy in mixing isn't good. It's just not something that you have to agonize about.

 

[jpdocdave]

I'm new to the site, and searching this topic brought me here among others. It's an interesting subject to me, I'm a mechanic, so I think about this stuff. Add the ethanol debate, which is all we have in my region, and it seems important to me. Too lean, burns up an engine, too rich and it carbons up and dies a different death.

Personally I have a new Stihl and a bunch of new Stihl synthetic oil I bought to double my warranty. Now I was practically given an older poulan pro 295 calling for 40:1. So should I mix two different cans, or is the synthetic Stihl oil adequate to run a 40:1 saw at 50:1?

Nice part was my echo weed whacker calls for 50:1 and I now have a 4 stroke leaf blower. I would love to keep using 50:1 if the old poulan will be cool with it.

 

[redoakneck]

Amsoil 70:1. Just stirrin' the potopcorn:

 

[MCW]

I know that if I run my ported 7900's on 40:1 with full mineral oil (the way they are tuned now) I get hard starting and carbon build up after about 15-20 tanks. Without touching the tune and swapping to full synthetic (both Castrol TTS and ALCO) I have never had these problems surface again. I do tend to run my saws on the rich side but not stupidly so. I don't run the TTS anymore as apart from being expensive the fumes are quite acrid and after 10 hours felling I was getting a good headache. The cheap as dirt ALCO made oil, branded as Jakmax in Australia, is excellent.
I do think people get a bit too excited with chainsaw oil sometimes and try to bring the dirtbike and full race bike mentality into what is a quite simple and understressed engine design by comparison.

 

[gmax]

Matt, I think we are the only ones here who use the Jakmax synthetic oil, it's good stuff and I can get it cheaper than Stihl mineral oil.

 

[MCW]

Matt, I think we are the only ones here who use the Jakmax synthetic oil, it's good stuff and I can get it cheaper than Stihl mineral oil.

Yeah under the Jakmax brand you'd be right mate but it's made in the US by ALCO so I'm pretty sure there would be a variant doing the rounds in the states. It's blue in colour if that helps any guys stateside.

 

[DFK]

Thanks for all of the replies.
After reading all of this I think 50-1 is what will be put in MS310 from now own.
My saw is completele stock with a factory, or at least dealer, tune on the carb so it not like it is a super screamer or anything... So 50-1 it is.

Thanks
David

 

[Schipp]

Yea?

opcorn: :0
Schipp

 

[Nitroman]

Supposedly ported saws run cooler, and since they move a greater volume of fuel mix through the cylinder, with a lesser proportion of it burned, why would they need more oil? Just curious.

More generally, the difference between 40:1 and 50:1 is much smaller than the difference between a saw that is properly tuned and one that is a bit too lean. Another point is that with more oil in the mix, there is less gas, meaning less octane. The fuel mix also cools the saw when the more volatile components vaporize inside the crankcase, so more oil in the mix means less evaporation and less cooling. So optimally one would run the highest ratio of fuelil that still provides sufficient lubrication. How to determine this optimal ratio? Lots of expensive empiricle testing of the sort done by engineers at the major chainsaw manufacturers. Those engineers say 50:1.

Now that is a fascinating concept there. How did you come up with that one?

As to the second. Oh dear. Google "octane rating" then come back. Second, the rating of the gasoline in the mix won't change with more oil, gas is gas. Just have less gas in the mix, and with a properly tuned motor, it won't matter. Now...as to how much power is produced...

 

[ncfarmboy]

One of the largest Stihl dealers I've spoken to said that most loggers in his area were running 50:1 in their 660 Stihls for years. This dealer found that internal wear was worse than the guys running richer oil ratios (down to 25:1) when saws were pulled down a few years later. Once this was realised basically all pro users in the area started running 25-30:1 in their 660's. Whether this even works out to be economically viable over the life of a saw I'm unsure. This dealership used to shift about 60 x 660's to loggers a season and serviced basically all of them. They should know what they're talking about.
It pays to remember that most of us here will never run a saw for enough hours to see any difference in wear between higher or lower oil ratios. It's easy to say that a saw looks great internally after 100-200 hours when pulled down but how many of us get the chance to compare two saws side by side with 1500 hours on each, both having run different oil mixes?
It's like saying that Stihl RSC is the best wearing chain on the market after only one cut.
Just putting that out there...

Several years ago I was @ my local saw shop for parts. Carl (owner) was talking to local logger. Overhearing the conversation the logger was saying he went through a felling saw every six mo.
at 50:1 using Husky oil. He doubled up to 25:1 and had been using the same felling saw for several years??????? I didn't go to 25:1 but I did go to 32:1 because I didn't want to have 3 different mix ratios for different equipment. Now running Husky XP @ 40:1. When I run out it will be Stihl Ultra. I want to see some oil on my piston.
Shep

 

[Slamm]

Just putting that out there...

Several years ago I was @ my local saw shop for parts. Carl (owner) was talking to local logger. Overhearing the conversation the logger was saying he went through a felling saw every six mo.
at 50:1 using Husky oil. He doubled up to 25:1 and had been using the same felling saw for several years??????? I didn't go to 25:1 but I did go to 32:1 because I didn't want to have 3 different mix ratios for different equipment. Now running Husky XP @ 40:1. When I run out it will be Stihl Ultra. I want to see some oil on my piston.
Shep

Quite interesting, I've run Amsoil at 80:1 for at least 6 months logging with ported saws, and one saw has since had another 2 years of rough use put on it with a range of 65-50:1 ratio'd mix, and the PC and rings look marvelous. Not bragging about Amsoil, just saying that I wonder how some of these people stay in business when their stuff blows up every 6 months or even every year.
Also ran several saws on Walmart SuperTech Outboard 2 stroke oil all through a summer of logging and this is what the Amish loggers were doing for years without any known problems, I still have some of those saws and they have no issues.

Weird,

Sam

 

[one.man.band]

i don't experiment anymore with different ratios.

supposedly optimum oil/fuel ratio is based on oil migration through the motor. (not my words).

these links may provide some information (from an 2-stroke oil blender).

www.tlr-online.com/yahoo_site_admin/assets/docs/Maxima_Tips.61180056.html

and here's one on oil migration times through the motor:

Tech Tips - Maxima Racing Usa - Overkill

on the second link, rpm's also are a factor.

 

[Schipp]

yea?

i don't experiment anymore with different ratios.

supposedly optimum oil/fuel ratio is based on oil migration through the motor. (not my words).

these links may provide some information (from an 2-stroke oil blender).

www.tlr-online.com/yahoo_site_admin/assets/docs/Maxima_Tips.61180056.html

and here's one on oil migration times through the motor:

Tech Tips - Maxima Racing Usa - Overkill

on the second link, rpm's also are a factor.

"So O.M.B., what ratio & oil do you use/run now? Please!"

 

[sbhooper]

It amazes me how this keeps popping up. The manufacturers are conservative because they don't want to do warranty work. They recommend 50:1 so that is where you should run the mix and I suspect that with even the petroleum junk it is conservative. Richer just makes more smoke and really is not going to benefit anything. Run what makes you feel good, but the owners manual is there for a reason.

 

[MEATSAW]

What sort of shelf life does the 2-cycle oil itself have? Synthetic vs. conventional?

Even ethanol-free gas can still go bad right?

My mix is always between 40:1 and 50:1 with either Stihl ultra or Husky LS. Unfortunately there is no ethanol-free gas anywhere within 200 miles so I just get 93 octane and use Stabil ethanol treatment.

 

[2dogs]

Here is a panel of experts discussing mix oil.

http://arboristsite.com/chainsaw/9499.htm

 

[Wicked500R]

I will stirr the pot deeper...Amsoil Sabre @ 80:1 run in all my 2 strokes

 

[MacLaren]

I run Klotz R-50 40:1 in my 660. In the 555 I am running VP94 50:1