Can I run a 40:1 two stroke on 50:1 premix?

The first two stroke I bought was a Husqvarna chain saw. It uses a 50:1 gas oil mix. Since then three more two stroke powered tools were added from Stihl and Echo. They all specify a 50:1 gas oil ratio. This makes it very simple because I can use the same mix in all machines and finding the little 50:1 oil bottles is easy. Recently my brother in law dropped off a used el-cheapo Weed Eater. Now my wife says she will use it if I get it running for her. As far as I know there is nothing wrong with it other than it looks like a toy next to a real string trimmer. The gas cap reads 40:1. So the dilemma is if I run it on 50:1 gas mix will it work or will it crap out before the first tank is run through? I’m wondering if anyone has any real world experience with this, if not I’m tempted to give it a try and see what happens. One thing is certain; I am not getting another gas can for 40:1 pre-mix, no way no how, not going to complicate my life more than it already is.

I don't think anyone will encourage you to run an engine with less oil than it calls for. I am in a similar, but opposite situation. I have two things that call for 40 & one that wants 50. I run all of them at 40 with no problem. I'm with you.... I'm not going to keep two flavors of oil mix.

< suggestion that you didn't hear from me: run it on 50, if it craps out the first tank.... " That's why he gave it to us, he knew it was about to die". >

As long as it's good synthetic 2-stroke oil you could run that at 100:1 if you wanted. So 50:1 is fine. Amsoil Sabre can be run at 100:1

50:1 = 2.56 oz. per gallon

40:1 = 3.2 oz. per gallon

Barely 7 tenths of an ounce difference.

100:1 = 1.28 oz. per gallon. Very economical!

Run OPTI-2, I use it and my Saw never ran better, one mix for all your gear...

http://compare.ebay.com/like/2706941278 ... s&var=sbar

I'm with Smitty regarding the synthetic. I have an old '90s vintage harness & bull horned straight shaft beast of a wackier that was sold through both Agway and Sears. The Fuji-Robins engine manual calls for something around 28:1 (?). It hasn't seen that ratio mix for years since I ended up with a few Kioritz engine powered tools that call for synthetic oil at a 50:1 ratio. I don't know how old it is, must be nearing 20, but the beast still roars ... and smokes a lot less too

One other thing I'd highly recommend: Good gas stabilizer. I use to run all my mix with an additional shot of stabilizer but decided not to once I saw the oil I bought had stabilizer in it. Experience finds it's not enough! When I got the little tiller out this spring, there was a few ounces of old gas in the tank which I dumped into an old clear bottle. There must have been at least 1/2 oz. of water in it that was absorbed from the air! It's never seen any weather except clear and the can I filled it from is inside all the time. Blame it on 10% Ethanol blends - back pack blower was exactly the same Now the can sees no more than 1 gallon at a time and I add 3x the amount of stabilize called for. I'll see what happens next.

Speaking of alcohol in the gas..... I finally made a few phone calls this week. There is an airport nearby that will sell av-gas for $5.85 a gallon. It has zero alcohol. Add Stabil to that & it should be like the good old days. I'm going to see about getting a couple of gallons for the weed whacker, chainsaw & Mantis tiller. The lawn mower uses too much fuel for through the summer, but maybe a gallon at the end of the season?

I agree with smitty I run 100:1 with amsoil in everything. no problems. actually i tried to mix it a little richer cause I was scared about 100:1 at first and it fouled plugs. I wouldn't worry about it.



Eric

I have an old gas powered hedge trimmer that is marked 20:1, It the hedges and smokes the mosquitoes at the same time

I have 2 lawnboys, a couple of trimmers, a mantis tiller, and a '78 evinrude on the boat. All of them get 50 to 1 and the correct amount of stabil. I never have a problem starting any of them... my $0.02. I use the cheap oil from wal-mart but probably shouldn't..

I never read what the manufacture wants, I have run everything at 32:1 since I was 12 witha honda 250r, lawnboys, chainsaws,leaf blowers and don't have any problems. The leaner mix I believe today is to satisfy the epa, stihl has started to make a 4 mix engine, 4 cycle that takes mix to help with emmisions. The epa is killing off the 2 cycle, no more 2 cycle lawnboys, dirtbikes , etc. I was never a fan of the idea of amsoil at 100:1, but to each his own, I'd rather burn oil and save the rings.

AA130FIREMAN wrote:I never read what the manufacture wants, I have run everything at 32:1 since I was 12 witha honda 250r, lawnboys, chainsaws,leaf blowers and don't have any problems. The leaner mix I believe today is to satisfy the epa, stihl has started to make a 4 mix engine, 4 cycle that takes mix to help with emmisions. The epa is killing off the 2 cycle, no more 2 cycle lawnboys, dirtbikes , etc. I was never a fan of the idea of amsoil at 100:1, but to each his own, I'd rather burn oil and save the rings.

I bought a Stihl FS-90R trimmer to replace the FS-36 that I'd had for a dozen years. The FS-36 still ran great, but one day I was trying to finish trimming and the head kept jamming up and wouldn't feed. I got so irritated with it I just bent the thing in half and stuffed it in the garbage can. It wasn't much of a loss since it really wasn't a Stihl but a Ryobi 31cc engine wrapped up in Stihl clothes.

Anyway, the FS-90 is a [url]serious[/url] trimmer and has that "4-mix" engine. It's very torquey and sounds a bit like a 2-stroke that is running too rich and "4-stroking". They recommend using the Stihl oil in the silver bottle, which I believe is a synthetic and is supposed to minimize carbon buildup on the valves. It's 50:1 and I can't see any visible smoke, but it does smell funny. I still run my Lawn-Boy at 32:1 with the Lawn-Boy oil to get my weekly whiff of nostalgia.

Well I just have to throw this in I'll go back to when my Grandfather was logging in Bucks County in the 20's--still using spring boards--anyway when 2 cycle came to be--a 2 gall. can of gas & a good couple glugs of 20 weight or tranny fluid had the saws running great--I have carried on that family tradition through the yrs--mostly Stihls (45's), some Jonsereds (90's)I've never had any problems starting them or anything other issues. I did weekly maintenance on them & all my daily used equipment. All this new fangled stuff befuddles me for the most part & you can take all that synthetic stuff and ----AND, don't get me started on EPA mandates

Sparkplugs are less $$$ and easier to replace than pistons,rings and scored cylinders.

Apples to oranges. The science behind the development of the synthetic oils is a world apart from what it was when there was only full-petroleum based oils. They do a better job of lubricating at a lower concentration and thickness (viscosity) at operating temperatures. Less carbon/sludge buildup and less oil to move out of the way. When looking at it from a micro view, newer oils have less tendency to spread out too thinly under the pressure of opposing surfaces under load. Picture a babitted surface bearing on a crankshaft.

Notice how the newer auto engines run on thinner oil blends? One of my fleet calls for 0-30. I read a long time ago how ruining higher viscosity oils or too much on the rings actually increases frictional heat. Excess heat means more wear. Using the lowest viscosity oil and the correct amount means less heat and longer ring life. Engines can be designed with closer gap tolerances which will last longer and run at higher RPM. Run these engines on higher viscosity oils than design means more heat and greater wear.

If I were to take everything I read as Gospel, I'd probably go broke trying to keep abreast of all the yearly " BETTER" products available. Hmmmm, are eggs good for me this year. I know whole milk isn't, but I've been drinking it for 66 yrs and those little see through motors on many parts counters that show viscosity effect??? if it works for you, that's what counts--I was just sayin I've never even seen 0-30 oil. I need to get off the hill more often I guess.