Sta-bil fuel stabiliser

[Gad]

Browsing through dec.QFM, on page 132 there is a write up on STA-BIL Fuel Stabliser which is now being imported from yankyland by Trico Products,that says if added to fresh fuel for inboards & outboards it stops fuel going stale in a p/tank for upto 12 months,and supposedly stops the formation of gum and varnish in engines.

The small article has more claims about the "goodness" of this stuff

Has anyone heard of this stuff,and if so does it work for 4 & 2 stroke engines.

cheers Gad

[baheath]

Hi Gad,

The MSDS for the product reveals little (to be expected). STA-BIL is about 95 - 98% solvent (mostly Heavy Aromatic Naphtha - containing about 5% naphthalene). The rest is likely to be primarily an antioxidant (probably butylated hydroxy toluene - BHT) and an ashless detertergent (DDI) package. There might also be a metal deactivator or corrosion inhibitor.

The "real" additive is the BHT - this stops the fuel from oxidizing in the tank and polymerising to form gum/varnish (black sludgy crap that fouls the fuel filter).

A product built like this should work for both 2 stroke and 4 stroke - as it only affects the fuel - but if you are using the fuel quickly (i.e. in less than a month between tank refills) it's really not necessary. Gum formation is a relatively slow process, though it speeds up in higher temperatures, exposure to UV and especially in the presence of dissolved copper. (I never have worked out why companies used copper fuell lines - just looking for trouble there!)

Out of interest, what are they charging for the product?

Regards

BAH

[Gad]

Thanks baheath,

The article did not give a price list,just that it comes in 118,236 and 473 mL bottles, 30mL treats 9.5 liters of fresh fuel.The write up said it will be available from leading marine and hardware outlets.

cheers Gad

[baheath]

Hi Gad,

Yeah, the treat rate sounds about right for a 1% BHT solution as the main active.

30 ml in 10lt = 3ml / lt = 3000ppm, so at 1% active that means about 30ppm BHT - enough to stabilze fuel for about 12 months under normal conditions.

We can make and sell an equivalent product for about $10 / litre (so about $50 for a 5lt bottle ex works). My bet is the STA-BIL will cost you about $5 for a 118ml bottle (4oz US) or $15 per 473ml (16 oz US) bottle in the store.

Regards,

Bruce

[shortie]

People have been ading moth Balls (Naptholane Based) to the engines for years to increase octane and HP in the vehicles.

My understanding was that it can put some sort of Iron deposit on your spark plugs and cause a misfire.

Remember some moth balls are not Napthane based.

Hower is does work as an octane booster. Also used is a substance called Ferrocene.

[Old Scaley]

baheath wrote:

Hi Gad,

The MSDS for the product reveals little (to be expected). STA-BIL is about 95 - 98% solvent (mostly Heavy Aromatic Naphtha - containing about 5% naphthalene). The rest is likely to be primarily an antioxidant (probably butylated hydroxy toluene - BHT) and an ashless detertergent (DDI) package. There might also be a metal deactivator or corrosion inhibitor.

The "real" additive is the BHT - this stops the fuel from oxidizing in the tank and polymerising to form gum/varnish (black sludgy crap that fouls the fuel filter).

A product built like this should work for both 2 stroke and 4 stroke - as it only affects the fuel - but if you are using the fuel quickly (i.e. in less than a month between tank refills) it's really not necessary. Gum formation is a relatively slow process, though it speeds up in higher temperatures, exposure to UV and especially in the presence of dissolved copper. (I never have worked out why companies used copper fuell lines - just looking for trouble there!)

Out of interest, what are they charging for the product?

Regards

BAH

Hey BAH, good to see a bit of science operating on the site. In your opinion, is it ok to keep topping up the tank (2 stroke fuel) rather than emptying completely between refills? I try to run the tank as low as possible between refills, but usually top up when there is under 10 litres in a 24 litre tank, so it is possible that some of the fuel could be quite old, although very diluted.

Cheers

Steve

[baheath]

shortie wrote:

People have been ading moth Balls (Naptholane Based) to the engines for years to increase octane and HP in the vehicles.

My understanding was that it can put some sort of Iron deposit on your spark plugs and cause a misfire.

Remember some moth balls are not Napthane based.

Hower is does work as an octane booster. Also used is a substance called Ferrocene.

Hi Shortie,

Naphthalene won't put an iron deposit on your spark plugs - but ferrocene may. Ferrocene is an organometallic compound used as an octane improver (Associated Octel - the people who put lead in petrol - produce it as a lead replacement additive calle Plutocene).

Ferrocene is a co-ordination sandwich compound formed between iron (Fe - hence ferro) and cyclopentadiene - when it burns it creates free radicals which initiate a faster burn in the combustion chamber - it may also leave behind a minute amount of iron. As the typical treat rate is about 30 ppm, and as most of the additive leaves via the exhaust system as microdust, fouling of spark plugs is rare. Octel have trialled the product extensively and it appears to be a "no harm" product in relation to ox-sensors and sparkplugs, etc.

The other common octane enhancer on the market is MMT (Methylcyclopentadienyl manganese tricarbonyl) a compound similar to ferrocene but with manganse replacing iron.

Regards,

BAH

[baheath]

Hi Gad,

Having a trace of old fuel in new fuel won't make much difference to anything - you just don't want to let fuel sit for, say, 6 months. There are a number of problems that occur :

Pure hydrocarbon fuels (i.e. NOT E10) will lose volatile components ("light ends") and the fuel can be difficult to start. There is also a difference between "summer" and "winter" grade fuels - in winter the refinery can add more butanes (VERY light ends) into the fuel, so, apart from losing more fuel through evaporation as the temperature rises if you DO manage to keep all the light ends in winter fuel through to summer you may then suffer vapour lock.

Unstable compounds (i.e. those that can oxidise easily) will form (a) peroxyacids [corrosive] and epoxides that can polymerise to gum / varnish. The BHT additive I wrote about earlier blocks the oxidation pathway to stop the epoxides forming polymer.

E10 obviously has other problems [water uptake, stability, separation, etc].

Regards,

BAH