E10 petrol and outboards

thinwater

Well-known member
Joined
12 Dec 2013
Messages
4,228
Location
Deale, MD, USA
sail-delmarva.blogspot.com
In 1995 Kevin Krause of the US EPA wrote an internal memo detailing the conditions necessary for phase separation (see attached). Depending temperature, about 0.3-0.45% water will cause separation. As a result, only absolute (not azeotrope) ethanol can be used.

In practice...
  • The E10 is not dry when you get it. It contains some tiny amount of water.
  • Most of the water gets in the tank through filler leaks.
  • Silica gel vent filters work great.
  • On portable tanks, keep the vent closed when not running.
  • You will most likely see separation when the temperature drops in the fall, because it has all summer to absorb water, and because tollerance is less when cold.
  • Aluminum corrosion is a problem even if not separated. The water increases ion mobility and carbs have aluminum and brass (a bad galvanic pair). The cure is an anti-corrosion additive, suc as Stabil 360 or Biobor EB.
  • There is no safe additive the will prevent separation. The are chemicals that will do it, but the engine manufactures have lobbied against them, because they can damamge the engine. Do NOT buy an additive that claims to help burn water.
  • Burn the gas through. Gasoline has never been the most stable stuff. Run the engine enough to burn through it several times each year.
I've been living happily with E10 for 30 years. You just need to follow the rules.
 

Iliade

Well-known member
Joined
27 Apr 2005
Messages
2,123
Location
Shoreham - up the river without a paddle.
www.airworks.co.uk
Apologies for re-awakening this zombie thread -

I have two different highly strung small (aero) two-stroke engines, both fitted with fine particulate filters on the fuel pick ups.

They each get run on about two days every month or so and after use I decant the fuel into a 25l plastic o/b tank to ensure I use it up a quickly as possible.

Neither have a tap fitted to allow running dry. ( I think I may have to fit one, but I could use hose clamp pliers in the meantime.)

They both suffer from what I believe to be gel formation in the carbs, clogging up the midrange (at which they are mainly run) and stopping the motors. They will usually restart easily at idle and I can then usually get the motor to suck the obstruction through by sealing the air intake while revving the motor. But doing so in a muddy field not of my choosing is irritating at best!

The carbs are factory sealed so I am reluctant to strip them if I don't have to. One is still in warranty.

Will any of the fuel stabilising snake oils actually help to prevent the gel formation and will any dissolve any gel which may still be present?

(eg: https://www.amazon.co.uk/Briggs-Stratton-Additive-Stabiliser-992381/dp/B003374F9E)

Thank you all in advance!
 

coveman

Active member
Joined
10 Apr 2016
Messages
558
Visit site
I get your point as I have a Yamaha two stroke with no drain plug on the carb. I run it dry but presume there will still be a small residue left. I am considering, before I put the engine way, running a bit of Aspen fuel through the system which should completely evaporate leaving no residue. However, Aspen recommend a mix of Aspen 4 + marine grade oil (50:1) so I am not certain that this would work. They do not recommend Aspen 2 which is ready mixed for strimmers, chainsaws etc. If your engines are air cooled then Aspen 2 should be ok.
Not sure whether any additives would work even though I use them but they are advertised as prolonging the life of the fuel.
 

thinwater

Well-known member
Joined
12 Dec 2013
Messages
4,228
Location
Deale, MD, USA
sail-delmarva.blogspot.com
Apologies for re-awakening this zombie thread -

I have two different highly strung small (aero) two-stroke engines, both fitted with fine particulate filters on the fuel pick ups.

They each get run on about two days every month or so and after use I decant the fuel into a 25l plastic o/b tank to ensure I use it up a quickly as possible.

Neither have a tap fitted to allow running dry. ( I think I may have to fit one, but I could use hose clamp pliers in the meantime.)

They both suffer from what I believe to be gel formation in the carbs, clogging up the midrange (at which they are mainly run) and stopping the motors. They will usually restart easily at idle and I can then usually get the motor to suck the obstruction through by sealing the air intake while revving the motor. But doing so in a muddy field not of my choosing is irritating at best!

The carbs are factory sealed so I am reluctant to strip them if I don't have to. One is still in warranty.

Will any of the fuel stabilising snake oils actually help to prevent the gel formation and will any dissolve any gel which may still be present?

(eg: https://www.amazon.co.uk/Briggs-Stratton-Additive-Stabiliser-992381/dp/B003374F9E)

Thank you all in advance!
It is not the fuel that gels per se. It is aulminum corrosion products, the result of having absorbed water (ethanol aids this) and brass/aluminum in close contact. The corrosion products cause clogging.

The solutions are to do everything possible to run dry fuel. For aero (if you are talking ultalight) the answer is to run non-ethanol fuel. If they are models, I would find a very dry storage location, including heat and silica gel as practical.

If you must run ethanol fuel, use an additive that prevents corrosion. Stabil 360 Marine (not the regular Stabil) and Biobor EB have tested very well for this (Practical Sailor). The rest are less effective and some are just snake oil.
 

Iliade

Well-known member
Joined
27 Apr 2005
Messages
2,123
Location
Shoreham - up the river without a paddle.
www.airworks.co.uk
Thank you Thinwater!
______

We stock plain vanilla Aspen (because I have heard that one should use the recommended 2T oil rather than the pre-mix Aspen). The trouble is, at £4/L I can't afford to use much of the darn stuff! Plus,it is a pain to drain the tank, then swap the pick up to an Aspen bottle. That said, I think I may just have to live with something like this, given the water/alcohol mix that gets sold as petrol nowadays.

Unfortunately, Avgas 100LL is too high an octane for the Vitorazzi motors, plus they don't like lead.

Now hunting for realistically priced Biobor EB in the UK...
 

thinwater

Well-known member
Joined
12 Dec 2013
Messages
4,228
Location
Deale, MD, USA
sail-delmarva.blogspot.com
Thank you Thinwater!
______

We stock plain vanilla Aspen (because I have heard that one should use the recommended 2T oil rather than the pre-mix Aspen). The trouble is, at £4/L I can't afford to use much of the darn stuff! Plus,it is a pain to drain the tank, then swap the pick up to an Aspen bottle. That said, I think I may just have to live with something like this, given the water/alcohol mix that gets sold as petrol nowadays.

Unfortunately, Avgas 100LL is too high an octane for the Vitorazzi motors, plus they don't like lead.

Now hunting for realistically priced Biobor EB in the UK...
Try Stabil 360 Marine. I think it is available in the UK. Get a tiny bottle.
 
Top