tdriver

how long do you keep your mix until you replace it with fresh one?
do you use any stabilizer like stabil to keep it fresh longer?

i 've read that 2 stroke oil already has some stabilizer in it is it true?

edit:
i'm using castrol TTS 40:1

w8ye

My Feedback: (16)

I keep the mix until I use it up. In this area, the gasoline is rather stable. Some areas, even in the USA, gasoline/oil mix does not keep very well.

Yes some two stroke oil has a stabilizer already in it.

TimBle

on the same can of RON95/Shell Advance Ultra now for over 2months.
I store it in the beer fridge in a metal fuel can. no problems

pe reivers

After mixing, the fuel starts degrading immediately. A fresh 1:50 mix 93 PON after one year of storage has degraded to about 90 PON and is equivalent to 1:100 mix.

TimBle

under what storage conditions?
how much air space above the fuel?

a degradation of 3 octane numbers is not unusual for fuel stored poorly.

MetallicaJunkie

i have a 2.5 gal gas can i mix 2 gal at a time 40:1 and refill it when it gets low enough that 2 gallons will easily fit.... it last about a couple of months and a 1 gallon container that i mix 3/4 gallons at a time in it for my DLE20 mix Stihl Ultra HP supposedly has fuel stabilizers in it

*edit i ve never had to empty my gas can because of bad fuel, with one exception, when i was using Amsoil 80:1

av8tor1977

My Feedback: (6)

One month.

AV8TOR

Andika

You are talking about Gas, however glow mix lasts years and years with no problems...

pe reivers

The way normal people store their fuel in the garage, waiting for the next use. Not in the fridge, container not full.

Tired Old Man

My Feedback: (1)

Which is all the more reason for people to buy premium grade gas instead of regular if they don't use up the contents of the can over the course of the the next few weekends. For me, it's not unusual to have the same contents in a can for up to 6 months, so premium permits extended storage time. To date I haven't had fuel 6 months or less in age cause any problems, but the can is well sealed and kept out of the sun. The storage environment rarely rises above 70F. Once past 6 months it works out for yard tool fuel with no notable ill effects.

Gray Beard

My Feedback: (-1)

I too have had it mixed for about 6 months and not noticed any difference in the way my engines ran. I'm in a very dry place though and my shop where I store my gas will get up to the high 90s and down into the low 50s. A bit lower in the dead of winter. I mix my gas one gallon at a time though if that has anything to do with it?

w8ye

My Feedback: (16)

I have a four liter can that I use for my Saito and the DLE 20 gas engines

I have a two gallon container that I use for all my chainsaws, weed whackers, and bigger gas model engines.

Sometimes they set partially full over the winter but for the longest point in storage.

pe reivers

I mix 5 liters at a time, and fill the mix in tightly capped 1.5 liter coke bottles, so no gas can escape. These are for transport to the field in my flight box . The remaining 0.5 liter goes into my current fill bottle and is used up first. This scheme has worked for me since the day I started flying gas engines (20 years now).
Old gas I do not trust, or experiment leftovers, goes into the four stroke lawn mower.

captinjohn

No extra gas here.....I use it up. Capt,n.

tony0707

HI
I HAVE a 2 gallon gas can with lawn boy 32/1 two cycle oil using it in my weed wacker for the lawn for 3 yearsno problems-did not know i had to be concernedi am in central flthe garage is 80-90 degrees in the summer months so conditions are nastybut can is always well sealed
BEST REGARDS TONY

mtnflyer14

This will be a little off topic, but what (if any) are the ill effects of running 40:1 two cycle mix in a four stroke lawn mower engine? I think I should be refreshing my two cycle gasoline for my ZDZ-80 and G-62 more often based on the information in this thread.
Regards,
Gus

pe reivers

The 4-stroke will see no ill effects. ALL good two stroke oils have extra detergents for protection against exhaust valve blocking, so the 4-stroke exhaust valve should be good as well.

For those who never had any problems with old gas mix:
I received this stale fuel information from a professional garden appliance maintenance center. They were the guys that got to service the damaged engines AFTER they came to harm. Up to that moment the engines run well of course.

RCER88

My Feedback: (25)

IF my gas lasts to the fall here in Michigan. I dump it in my ford tractor. I keep gas for airplanes one flying season. Then I burn it in the tractor.

Flyfast1

My Feedback: (1)

Interesting point about the degradation of octane. So, for the standard compression two stroke gas engines that we use, is there any harm in using the highest octane gas (assuming the additional cost is not an issue)? I currently use 87 octane gas. If I change to a higher octane level, say 91, do I need to check the tuning on all my engines? I use Stihl HP Ultra oil if that's important.

Thanks,

-Ed B.

pe reivers

Damage can be done using too low octane numbers. Using premium gas will do no damage at all. Racing gas is not needed in a model engine. The high octane numbers should be leadfree gas, or ignition reliability can suffer. (lead spark gap bridging)

BTW, what would be called "standard compression"? European engines all have higher compression and need at least 90 octane leadfree.
Before anyone jumps in and says "I dont have problems with 87 PON" it should be noted that at higher altitudes the effective end of compression pressure/temperatures are much lower, so using too low octane fuel will not be so devastating to the engine.

Flyfast1

My Feedback: (1)

Hi Pe,

I am not an engine expert, but what I mean by "standard compression" would be brands such as FPE (First Place Engines), Taurus, Zenoah and DA. If I switch my gas from 87 octane to 90 octane, should I recheck the tuning? I live in California, so I am guessing our so called unleaded gas is lead free, but I am not sure about that.

Thanks,

-Ed B.

pe reivers

California is not all sea level. Leadfree is no lead (free of lead)
find out what compression ratios your engines have. It is reflected by the octane number of the fuel required in the manual.
I have no idea of the FPE requirements or DA. I know about the engines I represent though. They NEED decent octane numbers. Not just any available fuel.

kmeyers

I keep mine until I run out.

av8tor1977

My Feedback: (6)

I used to be a "Authorized Rotax Service Center". Rotax are the two stroke engines that power about 90% of the Ultralight Airplanes. When I took the classes/course to become certified, they taught us that gas started degrading as soon as you mixed the oil into it, and that it should not be used after one month. Many of our model engines are not very octane sensitive, but there are some that are high compression and they can be. Those might encounter problems with old fuel, such as overheating, detonation, and eventual engine damage.

Not many seem to have the problems I encountered, but I was having problems with the diaphrams in my carbs going bad in as little as 4 to 6 weeks, and my fuel lines becoming so stiff the clunk line in the tank would was no longer flexible enough to work properly. It is not fun to have your engine die when doing a low level inverted pass!!

So what I did was go to using a "Storage Fuel". This I made out of Coleman Camp Fuel, 20 to 1 Pennzoil for Air Cooled Engines, and a dash of Sta-Bil fuel stabilizer. After I am done flying, I empty the tank and fill it about half full with my storage fuel. I then start the engine and run it just long enough to ensure that the fuel gets into the engine. I then leave the storage fuel in the tank until I am ready to fly the plane again, at which time I remove it and fill up with my flying fuel. A lot of guys consider this complete overkill, but it totally ended all the fuel system problems I had been having. Now my fuel lines and carbs last indefinitely.

Now this is probably going to start a Coleman Fuel "battle", but I absolutely do not recommend flying with the Coleman fuel. I notice that my engines run hotter just running them for a bit to get the "Storage Fuel" into the engine.

As far as my flying fuel, I stick with my "one month" rule. Anything over one month old gets disposed of and fresh fuel mixed up. How much does it cost to fly with fresh fuel??? Give your engine the best you can and it will reward you with good service.

Side note: When I have one of my flight fuel cans sit for a while without gasoline in it, the pickup line inside turns as stiff as a board in no time. (Doesn't seem to matter much whether the line is Tygon or Neoprene.)

AV8TOR

krayzc-RCU

My Feedback: (31)

Once it in my gas can I store it until I use it up. ...................................