Fuel Additives Follow-Up

Last month, an HVA e-news article entitled A Comparative Evaluation of Prevention of Gasohol Phase Separation by Fuel Additives generated a significant number of questions from readers interested in finding out more about how they can protect their engines from ethanol fuel damage.  We put some of these questions to the author, Benjamin Kellogg, who offered his response.

Benjamin Kellogg of South Texas became interested in historic vehicles through his family’s collection of old cars, which include a 1943 WWII Jeep and 6×6, light armored 1943 M8 Greyhound.  Regular maintenance and engine repair has long been a hobby for Kellogg and his father, who last year began wondering if fuel additives might help combat the inherent problems attributed to the ethanol fuel that had arrived at local gas stations.  With an equal passion for chemistry and access to a lab at his school, Kellogg decided to find out.  With the help of a local high school chemistry teacher, Kellogg designed a simple water titration study to objectively test the effect of the additives on phase separation.

Last month, HVA e-news republished the resulting article from those tests, which originally appeared in the Fall 2011 issue of Army Motors.  If you didn’t catch the piece, A Comparative Evaluation of Prevention of Gasohol Phase Separation by Fuel Additives, click on the story link and then take a moment to see Benjamin Kellogg’s answers to some of the most frequently asked questions sent in from HVA members.

What is the baseline dehydration (life) for the gas we used five years ago?

Kellogg: How long pure gasoline can be stored varies from a few months to a few years depending on the type of gasoline—aviation gas, for instance, is supposed to last longer—and the storage conditions (cooler is better).  Predicting how long it will “last” is difficult because it is hard to know how long the gasoline has been stored at the gas station.  The biggest problems with storing pure gasoline are: evaporation of lighter hydrocarbons; hydrocarbon oxidation; and ultimately formation of “varnish-like” gum deposits.  It is difficult to tell if evaporation has happened by simple inspection of a gasoline sample, but gasoline turns progressively darker as it oxidizes.  When gum forms, small pieces can be seen in a sample.  Gasohol is less stable than pure gasoline because ethanol will absorb water from the air, thus gasohol can be contaminated much more easily than pure gasoline. It is said that gasohol can be stored for up to six months, but I have not tested this.  Water absorption by gasohol is the problem addressed by the Eastwood fuel additives that I tested.

What is the impact of other fuel stabilizers (i.e. Sea Foam, Sta-Bil, Sta-Bil Marine, etc.)?

Kellogg: While I have not tested these products, they are supposed to reduce the risk of phase separation in the same way as the Eastwood products in my study.  Sta-Bil claims to have the same effects on phase separation that the Eastwood products have but, again, I have not tested Sta-Bil.  Both Sta-Bil and Sea Foam are mixtures of different hydrocarbons than the Eastwood product I tested.  Sta-Bil contains only one active hydrocarbon agent, while Sea Foam and the Eastwood products each contain three active hydrocarbon agents (although they are completely different agents).  Since the three products are all chemically unique, knowing which is superior would require a new comparative study.

What do your results show if the amounts of fuel additive are exceeded?

Kellogg: If the recommended amounts of fuel additive are exceeded, it seems likely that the amount of water that could be retained in solution before phase separation happened would increase in direct proportion to the excess amount of fuel stabilizer used.  I suspect that the recommended amount of stabilizer is based on the amount of water that would be expected to be absorbed in six months of storage.

If the two additives [tested] are chemically identical, why didn’t you continue with your test to determine if doubling the dose of each additive on its own resulted in the same increase of water retention as the combined effect revealed?

Kellogg: Doubling the concentration of each additive would be a logical follow-up experiment, but as this was not tested, a direct conclusion cannot be reached; however, based on chemical principles, doubling the amount of fuel additive should double the amount of water that could be absorbed before phase separation happens.  But, again, the experiment has not been done so one cannot be sure.

If doubling the dose resulted in increased retention of water in E10, would increasing the dosage continue to increase the effect?

Kellogg: Based on principles of chemistry, there should be a direct relationship between the amount of additive used and the amount of water retained so that doubling, tripling, etc. the amount of additive should double, triple, etc. the amount of water retained.

At what point would increased dosage become ineffective?

Kellogg: When the concentration of the additive became so high that the combustibility of the gasohol was decreased, the additive could be considered to be ineffective at preserving the fuel. Also, if the concentration of the additive in the gasohol ever exceeded the ability of the gasoline to dissolve the additive, the additive might phase separate from the gasohol and become ineffective.  But since they are both hydrocarbons, I doubt that would happen in actual use.

Are there any other studies you are working on?

Kellogg: I started a project for the Military Vehicle Preservation Association’s Army Motors magazine to look at the effect of DOT 3 versus DOT 5 brake fluid on natural rubber and synthetic rubber that has been going on for almost a year.  I have not yet analyzed the data, but results will be coming soon.

Can you reference any studies about whether hot weather has any impact on fuel component performance?

Kellogg: I live in south Texas, so doing something with heat and gasohol stability would be useful; however, my chemistry teacher and I decided heating gasohol in the chemistry lab could have a bad outcome so we only cooled it.

Reader note: What’s your experience?  Have you tried fuel additives in the engine of your historic vehicle and, if so, did they work?  Please share your experience with other HVA members by logging a comment here or on our Facebook page.

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