2-cycle engine gas

[Tdog]

I have a collection of brands of small engine tools/toys. Some call for a 40:1 gasil mixture; others, 50:1. Is that difference big enough to keep two different gas mixtures on hand? Or will running 40:1 in a 50:1 recommended engine [or vice versa] make a difference?

THanks,

Jack

 

[SPIKER]

this has been a debate here for a long while on & offf usually at start of chain saw season & weed eater season.

basically most everyone agrees that it is as much to do with the OIL used in the gas as it does the Mix ratio. (40:1 or 50:1 ect. I have several brands of 2 cycles, and poulan chain saws call for 40:1 while my homelight calls for 50:1 , so I buy good oil & run the lean mixture at the richer setting, which may make my weedeater run a little smoky but has not fouled a plug yet in 4 seasons, and same for chainsaws...

what is more importaint is to keep the air intake filters clean and the gas from getting stale, some oils have a gas addidtive to keep them from getting stale, (such as stabil-oil) the poulan oil does as does many others read the oil info to be sure...

mark M

 

[djradz]

Most new call for 50:1, mostly because the newer oils provide superior lubrication. The other day, the STIHL dealer informed me that their new, "low-smoke" formula was now synthetic. I'm pretty sure if you use a quality oil, such as that, you can run at 50:1 in almost everything.

 

[Highbeam]

The 2 stroke motorcycle guys have known for years that the mix ratio is very approximate. Some will run 80:1 mixtures in bikes asking for the typical 40:1 or 50:1. What I do for my collection of 2 stroke equipment is find the oiliest ratio of the bunch and mix it that way for all of them.

 

[geneP]

I have a Sthil chainsaw that I run more oil in the mixture than called for. I bought it in 1978, so I don't think a little extra oil hurts. It calls for more oil than my other engines, so I mix it like I will use it in the saw and put it in the others, too. I would much rather have too much oil than not enough.

 

[djradz]

I guess I'll quietly disagree. Premium chain saw companies, and even the folks using the saws competitively, recommend mixing right at the manufacturers recommended rate. Yes, you could probably run richer, but with oil that is designed to lubricate and then burn up at a certain rate, you just get more buildup and fouling of the piston, cylinder, plug and exhaust. I feel I get enough of that already and so I use everything at 50:1. Oil has improved so much since the older 2-cycle equipment was built, that the 20:1, 32:1, 40:1 rates are just obsolete anymore. If someone was really still concerned, the lowest I'd go would be 40:1 in anything, otherwise, just too much fouling and oily residue results.

 

[GaryM]

I used to use an oil called "one mix". I believe it mixes at 50:1. I use it for everything ccalling for 32:1 to 50:1.

It's a high quality low ash oil and works fine.

 

[Tdog]

Thanks all. My gut told me to mix for my 'favorite', which is my Stihl 026 saw @ 50:1. I guess the Craftsman leafblower & Ryobi weedeater will have to get by with the Stihl 50:1 low-smoke oil mixture.

Jack

 

[RobertN]

This is the way it was explained to me by an ex pro-motocross racer and engine builder. I have followed this since, with good results in dirt bikes, weed eaters, and chainsaws.

The oils are formulated to provide optimum lubrication at a specific ratio. ie 50:1. If you run it lean, you do not get proper lubrication. If you run it rich, you get more lube than needed, but also get more oil in the combustion chamber than needed too. This can cause carbon buildups, fouling plugs, and such.

Older saws, dirt bikes ect may call for 32:1, 24:1, 16:1. When those engines were designed and built, they were specced for the oil available at the time, and probably called for a specific brand of oil even. IF you found a can of that old oil, it would run fine at the spec, say 24:1. But, if you mixed it 50:1, it would be so lean for that oil formulation that you would burn your motor up.

Two other notes gleaned from him, and another friend who is an arborist. For the motocross races, they only ran gas mixed that day. They found that even day old mix did not run as well at race speeds as fresh. The oil does break down the second you mix ix, so that makes sense. For trimmers and saws, I only mix a gallon at a time so I keep fresher mix available.

The other thing was that trimmers and saws these days are 10,000 rpm motors. Use a good quality premium gas in the mix, and a good quality oil. Makes sense to me; if I was spun up to 10,000rpm I'd want a good fuel mix too /forums/images/graemlins/wink.gif

 

[BillyP]

The difference between a 40:1 and 50:1 mix is only .64 once of oil per gallon of gas. I doubt you or your engines could tell the difference.