Chainsaw oil/fuel mixture?

I hate to be the one to make a reccomendation that might ruin your saw. Older small engines like that used to be anywhere from 20:1 to 40:1. Newer ones do well with 50:1 mixtures.
But, still, I would check with the manufacturer to be sure. Small engines can be finicky. My Stihl heavy-duty brush cutter won't even start with anything other than Stihl oil being used.
 
Thanks for the quick answers guys! Looks like that I am going to have to look for the manual some more. I looked on line at the McCullock site but did not see an on line manual. I guess that it is a little risky to just guess. It is a 2004 model so I am thinking that 40:1 might be OK.
 
Here's the answer :

  • Any saw owners manual will qualify the mix ratio by saying to use "their brand" of two cycle oil.
  • If you read the back of any two cycle oil container it will have multiple ratios shown - why? ... marketing.
  • Mixing oils are made with different viscosities. Homelite oil used to be required to be mixed at 32:1. Stihl oils used to be required to be mixed at 40:1 and now Stihl oils are mixed at 50:1 - the difference is the viscosity.
  • A 32:1 oil mixed at 32:1 will give the exact same lubrication as a 50:1 oil mixed at 50:1 does.

So ..... if you buy oil which shows as having the leanest possible mix as being 50:1, then mix it at that. For a bit of insurance, make it a "bit" richer and mix it at 40:1 but don't mix it too rich. Fuel which has too much oil in it will not burn completely and will leave carbon deposits in the cylinder and crankcase, especially if it is run too slow and cold.

Now .... here's where I contradict myself :huh:, There are oils out there which say on their labels that they will mix at extremely thin ratios such as 100:1 and will also mix at very rich ratios as 16:1 - I leave those oils on the shelf - I tend to distrust those sorts of claims.

For your McCulloch, buy Stihl 50:1 oil, or Husqvarna 50:1 oil, or Castrol Super Two-Stroke 50:1 oil and either mix it 50:1 or 40:1 - I use Stihl at 40:1 in ALL my two-cycle equipment, even my old Lawnboy.

This is also how I've trained my customers to mix and after 17 years I've never had a customer have an engine failure due to the mix ratios I've provided.

cheers eh?
 
This is really great information!!!!! Thanks! Looks like that I am on my way, manual or no manual.

Model number is McCulloch CS 38 EM. Looks like that it is no longer on the market.
 
For my older saw, I ran it at 32:1 I think that is a very safe mix, but I will also bow to John's expertise, except, I like the smell of the Castrol Super oil :D

One more thing, the more oil in the mix, the less gas, so it actually runs leaner.

Cheers!
 
For your McCulloch, buy Stihl 50:1 oil, or Husqvarna 50:1 oil, or Castrol Super Two-Stroke 50:1 oil and either mix it 50:1 or 40:1 - I use Stihl at 40:1 in ALL my two-cycle equipment, even my old Lawnboy.

This is also how I've trained my customers to mix and after 17 years I've never had a customer have an engine failure due to the mix ratios I've provided.

cheers eh?

Now I know why my Stihl dealer told me to just use my 50:1 Stihl 2 cycle oil mix in my 40:1 Shindawa weed eater, which by the way, was purchased from him as well.

thanks for the explanation.

joe
 
Allen, all I do is mix one gallon of oil to one thing of 2 stroke oil. My old( 320 McCullough) runs fine like this and when I say old I mean 20+ old.:eek:
 
I'm with Stu, I mix 33:1 with decent Oil and hi grade gas for all my 2 stroke gear.

Manufacturers recommend between 25 and 50:1 :dunno:

So I split the difference and fill everything from the 33:1 .. with GOOD 2 stroke Oil

Cheers

Ian
 
I gave up on the high cost of expensive two stroke oil a long time ago. I run 40-1 in my Stihl and Husky saws and use standard mineral oil in my saws.

I do the same for bar and chain oil too. I got a 5 gallon bucket of the oil we used in the engines of the locomotives. Its a heavy weight, but cheap type of engine oil that they got by the tanker truck load.I suppose it wears out a bar quicker then the oil you are supposed to use because of the "sling factor", but does it really matter? Sometimes I wonder if we spend way too much money on oil (Stihl bar and chain oil is 4 bucks a gallon) to save something that only costs 30 bucks to replace. You would have to go through an awful lot of bar and chains in order to make the Stihl oil the better choice.

As a side note, after replacing just about everything in my shop, the only thing I have that is two stroke is my chainsaws. My snowmobile, my weedwacker, everything is 4 stroke, and just as soon as they come out with a 4 stroke chainsaw, I'll buy that too :)
 
One more thing, the more oil in the mix, the less gas, so it actually runs leaner.

Cheers!

You're right :) , but ... you also have to remember to qualify whether you're discussing mixture of "fuel to oil", or "fuel to air". In your sentence above, you're talking about the "fuel to air" ratio.

It's also true that fuel mixed with extra oil will take a looonnnngggg time to show any problems that may arise (unless the "fuel to oil" mixture is very rich). However, todays saws are metered so finely in the carbs, that we (in the repair shop) have experienced cases where a 2-cycle motor will come in running poorly (smoking, low on power) and we'll find that the answer is a simple as an excessive amount of oil in the mix combined with an owner who thought that running it at slow speed was good for the motor.

Travis spoke of running mineral oil at 40:1. Waaayyy back when I owned a Suzuki TC250 scrambler, I also used mineral oil, and found that when working the bike hard, my best power was found at about 25:1 - at the expense of a LOT of smoke - but remember, that was working it HARD!! If you run them slow and cold, they'll carbon up - 2-cycle engines are like diesels ... they like to work under an optimum load at rated RPM.

cheers eh?

EDIT :: for those folks who are reading this and thinking "I'm not doing that and I get along fine" .... please don't change just because you've read something different - if what you're doing is (and has been) working for you, then don't change just because you read this post from someone (like me) who doesn't know you, or your machine or how you work - keep doing what works for you .
 
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Yes John, you are right, thanks for that clarification.

Most of my 2-smoke experience comes from the two wheeled variety, I know a lot of guys who come from strokers that have trouble getting their heads around the idea that if you change the oil to fuel ratio from say 50:1 to 32:1 you have to use a larger main jet, as you have increased the amount of oil in the mixture, means there is LESS gasoline in the mixture.

Dunno why, but lots of guys seem to think that if you have more oil in the mix it would be "Rich" (speaking about the amount of gasoline to air mix) but in reality it is lean, as the added oil in the mixture bumps some of the gasoline out of the mixture........... I think.........

Cheers!
 
Now that you experts are here I have another question. I store my saw for long periods of time and leave some gas in it with Stabil and oil mixed in. I mark the date and change the gas mixture every twelve months and run it for a while before putting it away again. Is it better to store it this way or should all of the gas be drained out? If I drained out all of the gas that I could get out and run it until it stopped would it be OK to store it for even longer periods?
 
Allen, to be really honest with you, I don't really know which one is better.

Like your saws I have this problem with my snowmobile. In the winter time I use it long and hard and pound the miles to it. The when the snow melts it sits...and sits...and sits for 9 months or so.

Now I have used Stabil in my snowmobile gas in the past, and I have also just let it sit with nothing in the gas. To me it seemed both had the same result. The carbs would varnish up with bad gas...and while the sled would run, it ran crappy. It did the same thing with stabil in the gas.

I no longer use stabil in my gas tank come Spring. It seemed to me just running old gas in it made the engine cough and sputter for awhile, but not nearly as long as running a whole tank of gas filled with stabil. Now they do recommend that sled owners use a fogging oil. You spray your carbs with it come spring, and its supposed to keep air and moisture from forming inside the engine as its stored. My results with this have been less than spectacular. Like the stabil, it took forever to burn that stuff out of my engine.

If you are still confused Allen, you should be, because I just don't know. I am just telling you what I have had for experience with storing my sled for long periods of time. I have yet to find out a truly good solution to my long-term storage problem. Its frustrating because its a $9,000 dollar snowmobile with a pretty technologically advanced engine, its in my best interest to store it properly, and yet no real good solutions seem to exist. I can see you are in the same boat with your chainsaws.
 
I run everything at 32:1 from my old .075 to the new MS270
The oil comes from tractor supply, been running it for years.

As for bar and chain oil, I run bar oil from tractor supply also. Get it in the summer it's usually on sale at around 4 bucks a gallon. The difference, all my saws have the original bars on them yet. The wifes cousin runs motor oil in his saw for bar oil. I have to dress his bar three or four times a year, mine get dressed up once a year and I cut way more firewood than he does.

Motor oil slings off the bar way too easy, lack of lube leads to hot chains, hot chains stretch.
 
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