2-cycle engines and oil ratios

[donald girod]

I have four machines with 2-cycle engines. Two of these need 50:1 mix and two need 40:1 mix. It is obviously a pain to try to keep various oil mixtures around, so I have always just gone with 40:1. What is the downside here? The engine which wants 50:1 will be running slightly lean, since it expects 98% gasoline and is getting 97.5% instead. This sounds rather a negligable difference. It will also have more oil than it strictly needs, and should therefore smoke a bit more and might get a dirty sparkplug sooner than it should. Anything else?

Somebody who cuts a lot of firewood told me that he always just uses 32:1 regardless--he says the smoke keeps the mosquitoes away.

[Stormin Mormon]

Ah, one of the age old questions. I think they found this same question on the inside walls of the Egyptian pyramids.

The short answer is that richer (smaller first number; more oil per galon) won't hurt anything. Little more smoke, maybe spark plug fouls sooner. I knew a guy who ran 16:1 on everything, he did have some smoke, but never burnt up anything.

Leaner (larger first number, and less oil per galon) risks engine damage.

Tip: When you make the mix, pump some gas in your gascan, and then add enough oil for the gas you pumped. Screw the cap on, shake the gascan. Every time you are right about to pour the gas into the machine, shake the gascan. Helps mix the oil. I don't know how much of a problem settling is, but why risk it? Shake the gascan again!

[xrongor]

its fine. i keep 40:1 mixed and use it for everything. just dont put 50:1 in something that needs 5:1 or visa versa.

randy

[davefr]

Ratios are more determined by oil technology then engine technology.

I use Mobil MX2T and mix it at 40:1 with fresh premium fuel and use it for everthing. It's one of the best 2 cycle oils out there.

[BinaryBillTheSailor]

Running with too much oil in the mix causes lower operating temps, and faster carbon buildup in the combustion chamber, and also the rings. You can do it, but it isn't really the best for the engine.

BB

[m Ransley]

Alot of the 50-1 move is for pollution laws but at motor expense. Synthetic is best above 32-1 and proven engine life. A motor set to run at 50-1 will carbon and need to be reset at 32-1 and need a hotter plug. I feel safer at 32-1, Evanrude backed off its lean oil ratios because of seizure. If you need less oil than 32-1 for good engine life use synthetic. I think 50-1 is to lean for maximum motor life. My Echo, Lawn Boy and Sthil use 32-1. I never lost a motor.

[GVecere]

"The short answer is that richer (smaller first number; more oil per galon) won't hurt anything" Not totally true when you talk about rich and lean you are not talking about oil to gas ratio it is air to fuel ratio adding more oil does add more luberant but reduces the amount of fuel causing a leaner air fuel mixture and if extream enough causing increased cumbustion tempituers, detination and engine damage. very bad in high hp dirt bike engines and outboard motors (big outboads love to burn power heads) probably get away with it in a chain saw or weed wacker. Gary

[m Ransley]

Wrong Gv cere More oil doesnt make a motor run leaner, More Air does. Stoichmetric balance of fuel - air as determined by the carburator . More Air raises temps not oil. As wil altitude affect what is required Mini 2 strokes RC are critical as the only way to monitor them before meltdown is with a IR temp gun or wired probe. Get a temp gun for 20 bucks and try it on your lawnmower, Mix 50-1 then pour in oil to 32-1. then pull the air filter. You will see the rise fast. To much oil and you carbon to litte and no lubrication.

[Mango]

man, my toro has used 50 to 1 for 14 years now...still runs great...

[m Ransley]

Toro 2 stroke is a lawn boy motor . You would of got double the life at 31-1. EPa Califfornia rules.

[Mark]

For all of my 2-cycle engines (weedwacker, blower-shredder, chainsaw), I've used something called "one-mix" for all of them even though each of them requires a different ratio. I've been doing this for about 8-10 years, and they all seem to be working just fine. And, the best part, I only have one gas-can to fill and worry about. I get one-mix at my local lawnmower shop.

32:1 > regardless--he says the smoke keeps the mosquitoes away. >

[m Ransley]

32-1 is optimal but CAs pollution laws --- 2 stroke view is 4 stroke is best advisory prompted 50- 1 BS, in alot of mnfgs , but Bearings are the same, less oil = more wear.. 2 stroke pollute. 30 x as much as 4 strk 2 strokes time is limited and should be banned as pollution w 2 strokes is 30 x greater, boats and all. period........

[Gary]

That is what I am saying if you go from 50-1 to 32-1 you will get less gasoline in your mix and more oil for each given intake cycle leaning out the air fuel mixture. pulling the air filter too will make you even leaner and increase combustion temps.

Regards Gary

Storage Sheds for the NY tri state area

[m Ransley]

Going from 50 -1 to 32-1 wont change air fuel mix but oil fuel mix . You are not changing fuel input metering. That is done by carb needle valve settings. Or dirty air filters. Most new equipment have locks on them to limit range or none to set. Factory set , so it makes using a richer oil amount difficult. if not impossible.

[m Ransley]

Oil doesnt burn like gas , most is for lubricant and smokes because its unburned. That would richen a mix lowering temps, because its not burned and hasnt generated the heat the gas has. In RC motors a higher Nitometane level raises temps with the same oil as lower nitromethane brands . The fuel generates 98% of the heat.