2-stroke fuel--different oils for different applications?

I have a variety of 2-stroke engines and none of them get enough use to keep the fuel fresh per typical online recommendations (the ones that claim major octane drops after only a month of storage).
I have air-cooled chainsaws, string trimmers, backpack blower, outboards (Tecumseh powerhead) that need "ordinary" oil in the gas. Fortunately all require ~40:1 mix!
Water-cooled outboards that require marine TC-W2 oil mixed with gas.
An air-cooled direct-oil-injected Rotax project gocart that I'm not sure WHAT oil to use since it's a re-purposed air-cooled cold-weather engine in a hot environment.

Keeping track of these mixes is ridiculous--but there's a lot of online cautions NOT to trust the "one mix" oils that claim to work in all temperatures and all ratios.

What does everyone else do to deal with this?

 

I don't have the variety of engines you describe but there's some generally accepted rules to follow. First and foremost, there are two types of 2-stroke engines covering most equipment: marine (water cooled) engines and air cooled engines. It is best to maintain separate mixtures for these types of engines.

As far as mix is concerned, staying around 40:1 should have a minimal impact on the equipment itself and will mostly result in differences in smoke and spark plug replacement. I keep some measuring spoons on a nail by my workbench and have a chart taped to my wall with mix amounts at several volumes. I keep a few 1-gallon gas cans so I have no problem mixing a gallon or 1/2 gallon from a larger container in a minute or two.

Synthetics and para-synthetics have their place and you should consider them from the perspective of providing less sludge. However, I wouldn't use them universally and never assume synthetics allow me to postpone maintenance.

One point to keep in mind regarding octane is that many (but not all) 2-stroke engines require higher octane fuel, not because of the compression but because oil in the mix tends to reduce octane. Although counter-intuitive, I believe it to be true.

Lastly, don't keep gas in the fuel tank any longer than necessary and don't mix more than you will need beyond 30 days. I never mix more than a gallon at a time. Even when I'm away from home for while, I'm prepared to mix what I need as I need it. Also, use a product like Sta-bil. Beyond that, if it turns out $1 worth of gasoline mix must be brought to the dump, so be it.

 

I run Stihl HP Ultra oil in my 2 stroke gas and use it with all my 2 stroke engines regardless of what the manufacturer says. It's a high quality synthetic so even though it's ratio is less than needed for some tools it still performs well and I've never had an engine fail. Using the same fuel in all my tools helps insure that the fuel gets used and stays fresh.

As for your direct injected Rotax I'd search online to see what's recommended for oil. You could even take guidance from the Rotax aircraft engines as they are worked hard and often in hot environments.

 

While I only mix a gallon at a time I often have 2 cycle fuel stored for 3-4 months and never have any issues. Whenever I don't expect to use up the mixed gallon shortly I always add StaBil to it. I do use non ethanol only in my small engines.

 

Mark, I've considered using a pre-mix ethanol free can for my chainsaw because I occasionally travel with it. But I got the impression you use it in all small engines like a mower or snow thrower. I know there's a downside to ethanol in small engines and some people have had problems but for me that seems to be pretty expensive as there are no gas stations in Connecticut selling ethanol free gas.

What's your thoughts on additives like Sta-bil 360 to reduce the impact of ethanol?

 

I've only used the regular StaBil. I don't always use non ethanol in my lawnmower but always use it for my chainsaws, weedeater, leaf blower and pressure washer. I used to run ethanol gas in all my small engines but then I had a Sthil saw that while several yrs old had low hours [original bar, 2nd chain] that quit running. Since I seemed unable to fix it I put it in the shop and they said it was wore slap out and not worth repairing. I don't know that ethanol was the culprit but I always used the proper oil mix and doubt I ever ran out a full tank during one use.

I don't know if it's a nationwide web site or just local but I found a site that listed all the local stations that sell non ethanol gas. Haven't looked in awhile as I know where all the ones are that are somewhat convenient for me.

 

I was interested in using Amsoil Saber synthetic 2-cycle oil. They claim it's engineered for 100:1 regardless of what the engine "needs", and works on air & water cooled without causing coking or carbon build-up. I did some online searching for info but the more I read the more confused I got. It seems most gearhead forums dissolve into chaos any time oil is discussed.

 

"I was interested in using Amsoil Saber synthetic 2-cycle oil. They claim it's engineered for 100:1 regardless of what the engine "needs", and works on air & water cooled without causing coking or carbon build-up. I did some online searching for info but the more I read the more confused I got. It seems most gearhead forums dissolve into chaos any time oil is discussed."

To my knowledge, neither the Petroleum Quality Institute of America (PQIA) nor any other independent organization has done a comparison of 2-stroke synthetics. As a result, companies make whatever claims they're comfortable with and consumers have difficulty figuring it all out.

Of course Amsoil is a well respected player in the synthetic oil marketplace with an established record. As a personal preference, I believe there are better synthetics available today (PQIA does publish comparisons of motor oils, including synthetics.) and use those products in everything. Having said that, although I don't use Amsoil synthetics, I'd have no issue with them in general. When it comes to 2-stroke engines I'm confident Amsoil is fine but I prefer Royal Purple synthetic. I still mix consistent with the manufacturer's specs and change oil as if I was using mineral oil.

 

Maybe I should change my approach. I could keep 3 different containers of oil but only 1 gas can for 2-cycle mix. I would then just mix only what could be put into the tank as needed.
This just means I'll need to be more accurate and keep a table handy for mixing small quantities.

 

I read all responses from PD, Tony P and Marksr, all have good points and are all correct. With that many engines to service I would go with your last post. I would also try to keep each engine in either a fully empty state or full tank state when not in use.

 

I thought I was done here, but Norm mentioned something beyond 2-stroke engines I want to reiterate:

"I would also try to keep each engine in either a fully empty state or full tank state when not in use."

Putting aside keeping up with maintenance, focusing on the fuel in any small engine may be the most important thing you can do. Gas at your pump today contains 10% ethanol which can be harmful to small engines for several reasons. One of those reasons relates to the ability of ethanol (simplistically speaking) to pull water from the air; important in small engines because their fuel systems are vented, allowing air to get in.

Therefore, you want to keep the tank full in order to minimize the air or keep it empty in order to eliminate the ethanol. Thus, I keep my blower, mower, and trimmer full in warm weather because I use them regularly (and don't want to bother emptying and filling) and keep my chainsaw empty because it may go quite a while without use and emptying it is fairly easy.

 

I also thought I was done here but Tony's post raises another question:
What do you all do with the extra pre-mix?
Either fresh when you mix too much, or old when you're wanting to empty the tank.

OK to add it to my car & burn it up on the highway? My assumption (uh-oh) is there's no harm from a relatively small amount of oil & stale gas in my large tank...

 

I wouldn't hesitate to add a gallon or less to a tank of gas in any of my vehicles although I've never had any issue with 2 stroke gas being stored for several months [with StaBil added]

 

Sorry guys, but I can't imagine putting gas in my car that's not good enough for my blowers. For me it's easy to only make 1 gallon at a time so I seldom have more than $1 worth leftover.

The same applies to gas when I empty the tank.

Bringing it to the dump is easy. I save large screw-top wine bottles that a fill and take to the dump around once a year.

 

Agreed. A multi cylinder engine can handle an occasional gal of old gas.

 

I hope you mean a recycle facility and not a dump. Besides hold on to multiple bottles of old gas is not my idea of safety.

 

And there are no such recycle facilities near me. Not going to store it for the annual special day when they let you bring volitiles.