E-10 Fuel Additives that Fight Corrosion

Video E-10 Fuel Additives that Fight Corrosion
E-10 Fuel Additives that Fight Corrosion


Sensible Sailor has twice checked out gasoline components in recent times. In November 2008, we regarded on the capability of gasoline components to forestall the doubtless damaging water “drop out,” or separation, that happens in E-10 fuels (gasoline that has 10-percent ethanol content material) which are saved over lengthy intervals. In July 2009, we checked out diesel gasoline components that declare to fight organic progress. On this check, we once more take a look at gasoline components, specializing in the flexibility to forestall corrosion, which might result in damaging steel and strong deposits within the gasoline system.

Anybody who has needed to rebuild the carburetor on a small outboard is conversant in their affinity for choking on the smallest of deposits or tremendous solids. In diesel engines, these deposits seem within the gasoline tank over time, the results of gasoline oxidation, soiled gasoline, and bacterial progress. However important buildup in gasoline tanks is uncommon. Within the case of diesel engines, multi-stage filtration is usually adequate to catch the solids. In gasoline engines, nonetheless, solids usually seem spontaneously within the carburetor bowl, irrespective of what number of filters are employed.

For this check, PS checked out composite samples taken from 4 engines, none of which had used aftermarket components: two 2001 Yamaha 9.9-horsepower four-stroke engines, one 2006 Mercury 6-horsepower four-stroke, and one 2002 Mercury 3.5-horsepower two-stroke. We discovered the next contaminants, expressed as a proportion of whole weight: aluminum, 21 %; zinc, 8 %; calcium, 10 %; iron, 5 %; copper, lower than 100 components per million (ppm).

The mere presence of a metallic aspect within the solids doesn’t show that they got here from corrosion. These solids might have been launched throughout refining or distribution after which deposited within the gasoline tank over the course of years of evaporation cycles, however given the everyday ash content material of gasoline, this appears extremely unlikely. There are additionally polymer components that may dry out, forming a gel. Some research have reported sodium salts in gasoline.

The presence of aluminum warrants particular dialogue. Each gasoline tanks and carburetors usually comprise aluminum, and the gasoline additive ethanol has been linked to aluminum corrosion. With out delving too far into the chemistry, ethanol behaves as a weak acid, attacking the oxide coating that usually protects aluminum from corrosion. This exposes a reactive aluminum floor that the dissolved oxygen present in water can rapidly oxidize. Within the absence of oxygen, ethanol itself can function the oxidant, although this course of is far slower.

If circumstances are proper, this two-step chemical course of produces pitting that may, over time, bore holes by means of a gasoline tank. Corrosion byproducts can clog small passages. Corrosion inhibitors, usually added throughout refining, will gradual this course of to a crawl. We wished to search out out whether or not after-market components added additional safety.

There may be additionally galvanic corrosion to think about. The entire carburetors examined contained some brass components, and the Yamaha engines have brass drain plugs. The distinction in potential between aluminum and brass on the galvanic scale is 0.45-0.5 volts, relying on the precise alloy; brass and aluminum are well-known to be reactive when positioned in touch. In dry gasoline, nonetheless, there isn’t any conductivity and no corrosion, so earlier than the introduction of E-10 gasoline, galvanic corrosion was a small challenge. E-10, nonetheless, can dissolve important atmospheric moisture and saltwater in small quantities, and this water is transported all through the gasoline system. On this manner, E-10 delivers the important thing ingredient for gasoline system corrosion: water.

Testing Corrosion Resistance

Laboratory corrosion testing is a really well-developed science. The American Society for Testing and Supplies (ASTM) and Nationwide Affiliation of Corrosion Engineers (NACE) have volumes on these strategies. Nonetheless, their focus is completely different than what we want to obtain. Laboratory strategies usually give attention to product growth and high quality management. Check circumstances are made extreme, so the outcomes might be obtained inside just a few weeks at most. This permits labs to rapidly and economically kind by means of candidate formulations and check product batches. These accelerated strategies can’t all the time precisely mannequin the gradual processes and chemical breakdowns that happen over months and years. They usually pressure failures that don’t truly occur and overlook extra refined however lifelike failures modes.

For instance, in 1995, Normal Motors launched a revolutionary product, Dexcool. Whereas it had been the topic of in depth laboratory and fleet analysis, they by no means examined it with sure gasket supplies nor combined with every other coolant. In consequence, many vehicles suffered gasket failures and any topping off with different engine coolant was a catastrophe. The coolant has since been reformulated.

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E-10 Fuel Additives that Fight Corrosion


How We Examined

Our authentic purpose was to run a long-term check of gasoline components. As an alternative of including warmth or oxygen or extreme corrosive supplies, we might substitute time. Within the pursuits of gathering managed repeatable information, we took a laboratory-style strategy that included strategies used for testing engine coolants and gasoline components. The nuts and bolts of the testing process are on web page 17.

Initially, we examined E-10 gasoline with none water or additive additions, however after six months of publicity in humid circumstances, we discovered no measurable corrosion. The corrosion inhibitors within the retail E-10 had been efficient in stopping harm. In case you are meticulous about your gasoline (see “Upkeep Ideas,” web page 19) and retailer it for not more than six months, there needs to be no want for an additive. Nonetheless, we all know corrosion happens.

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Thus, we elected so as to add a small quantity of seawater—solely 0.03 % (the equal of three/4 of an oz of seawater in a 20-gallon tank, an quantity E-10 can simply maintain in answer)—to rush issues alongside. It’s our perception that severe corrosion in carburetors is uncommon and doubtless solely happens when both a whole lot of atmospheric water or hint seawater mist sneaks into the tank. That’s when a carburetor wants defending.

Our choice to speed up testing targeted on the flexibility of components to withstand salt-induced galvanic corrosion, a situation that some additive makers criticized as unrealistic, one which the merchandise weren’t designed to fight. We’ve included maker feedback relating to the check beneath the associated part for every product.

It’s potential that our closing rankings can be completely different if we thought of solely the corrosion brokers within the E-10. It is usually truthful to say that these components that skilled solely minor failures are prone to be enough beneath regular circumstances. Nonetheless, since all samples had been uncovered to the identical harsh circumstances, we imagine our relative rankings are good information for shoppers—notably when one considers the dangers of contaminated gasoline for a cruising sailor.

It’s our hope that because the marine gasoline additive business makes an attempt to reinforce requirements for these components, they may take a better take a look at our check for brand new benchmarks.

We chosen a bundle of ordinary, 1-by-2-inch, alloy coupons as utilized in ASTM methodology D1384—a glassware methodology for evaluating engine coolants that was modified to serve our check functions. This strategy ensured uniform steel alloys of identified composition. Moreover, these coupon bundles are designed to imitate the galvanic corrosion results widespread to machines assembled from dissimilar metals. The couplings used had been aluminum/brass/metal (to imitate a carburetor bowl) and copper/metal/brass (to imitate a metal tank and gasoline traces).

As acknowledged, we most popular extra lifelike publicity to the ambiance and an extended time interval for testing. Customary strategies require beginning with gasoline and pure ethanol with none refiner components, however we didn’t assume that check, whereas tremendous for refiners, was legitimate for testing aftermarket components utilized by boaters. We selected to check retail formulated E-10 (10-percent ethanol) 87 octane gasoline from a busy Shell Oil vendor.

What We Examined

The entire merchandise examined make basically the identical suggestions and claims: that the product needs to be used frequently and particularly earlier than long-term storage and that it prevents ethanol breakdown, gum formation, retains carburetors and injectors clear, and promotes simpler beginning. All however one declare to forestall corrosion; the opposite implies this. We solely examined the anti-corrosion assertion, and we solely examined merchandise marketed as storage components. We dosed every additive in keeping with label suggestions.

In all, we examined eight merchandise from eight producers, representing a cross-section of what’s available on the market: Hammonds Biobor Ethanol Buster; CRC Part Guard 4; PRI-G; Mercury Marine Quickstor; Sea Foam; Sta-Bil Ethanol; Star Tron Ethanol; and ValvTect Ethanol.


The sealed management pattern appeared to not age in any respect, and there was no corrosion or staining of the steel coupons. Clearly, something you are able to do to reduce water acquire and respiratory will assist forestall corrosion.

The vented management pattern with out seawater addition confirmed nearly no corrosion after six months of publicity. For the reason that atmospheric water absorbed by means of the vent is distilled water, which has very low conductivity and doesn’t encourage galvanic corrosion, the harm was minor.

The vented management with seawater addition confirmed quick corrosion, notably on the aluminum coupon. Brass and copper confirmed heavy staining, and there have been tiny pits on the metal coupons. The discoloration and pitting resembled that of the worst carburetors and gasoline parts now we have seen in 15-plus years of marine service. Some mechanics we spoke with reported pin-holes in carburetor bowls, and our mannequin appears to symbolize a practical worst-case situation.

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Saltwater intrusion is clearly harmful, even in minute quantities. Each effort needs to be made to insure that the filler cap is tight. There have additionally been reviews of sodium salts in E-10 that could possibly be equally dangerous, and as one maker advised, have damaging penalties when mixed with an additive.

Inhibitors diversified of their effectiveness. Even with salt additions, some had been capable of suppress practically all corrosion. Some had no impact in any respect. We had been shocked by the severity of the harm, and ran duplicates to verify our findings; the duplicates confirmed no important deviation from the originals.

Biobor EB

Biobor EB is made by Hammonds, the producer of Biobor JF, which is essentially the most broadly used biocide for diesel and jet gasoline, and a Really useful product in our diesel biocide exams. It appears clear the corporate has one other winner right here: Biobor EB (ethanol buster) is a top-performing additive with no steel harm and solely the slightest staining in our exams. Biobor EB is offered in 16- and 32-ounce bottles.

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The maker counseled our check report as “thorough and professionally performed.”

Backside line: Fairly economical and clearly the highest performer, that is our Greatest Selection.

CRC Part Guard 4

CRC Industries claims its Part Guard 4 helps droop water and delay part separation. Maybe that is its downfall, because it carried out poorly, with heavy aluminum pitting and heavy staining on copper and brass. It’s obtainable in 8-, 16-, and 32-ounce bottles.

Adam Seilisker, vp of know-how for CRC, took challenge with our check regarding the arbitrary alternative of .03 % saltwater answer and the small pattern measurement, amongst different issues. He mentioned a check utilizing dissimilar metals “introduces complicated reactions that may not be reflective of the atmosphere being studied. . . . We’re assured that CRC’s Part Guard 4 product meets all the efficiency standards for its supposed function.”(Right here is the complete textual content of CRC’s assertion: CRC Feedback)

Backside line: Not really helpful.

Mercury Marine QuickStor

The Mercury Marine Quickstor turned out to be a really strong performer and is made by a revered outboard producer. Quickstor confirmed a bit extra copper staining than Biobor, however there was no steel harm, and it had very clear aluminum coupons. (Aluminum was persistently essentially the most tough steel to guard.) It is available in a 12-ounce bottle.

Backside line: Quickstor was the costliest of the group, and whereas we advocate it for its strong efficiency, there are cheaper alternate options.


Testers famous heavy staining and important aluminum pitting within the PRI-G pattern check. The product was proven to droop water in prior Sensible Sailor testing and appears to be damaging within the presence of seawater. It’s obtainable in 16-ounce, 32-ounce, and 1-gallon bottles.

Ralph E. Lewis, a vp with PRI-G, questioned the extent of contamination in our check, calling it “extraordinarily uncommon,” however including that “ought to a seawater intrusion happen, the extent of contamination can be far greater than the quantity you used.”

He pointed to the product’s in depth standards-based testing and document with industrial purchasers, together with “greater than 1,500 oceangoing vessels—each distillate and heavy fuels. . . . Sensible Sailor may as properly have designed a check to find out if PRI-G makes a superb topping for vanilla ice cream.”

Backside line: Not really helpful.

Sea Foam

Sea Foam was a pleasing shock, as it’s not referred to as a marine storage additive, however fairly as a therapy for hard-to-start engines. Actually, don’t search for it on the marine middle in any respect, however fairly on the neighborhood autoparts chain retailer. The Sea Foam check coupons had been all very clear, and the gasoline had little or no colour change from getting older.

Backside line: Probably the most economical alternative and a high performer. It’s our Price range Purchase.

Sta-Bil Ethanol

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From Gold Eagle Merchandise, Sta-Bil is probably the most effective identified model of all winter storage components, and the particular marine components for ethanol fuels that we examined is broadly obtainable. This was our top-recommended additive for ethanol fuels within the 2009 check. Whereas this product has a powerful repute as a gum-preventing storage additive, it didn’t carry out in addition to others in corrosion prevention on this particular check. It did assist, although, and we imagine it will carry out properly within the absence of seawater contamination. It’s obtainable in 8-, 16-, and 32-ounce dispenser bottles.

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Backside line: Whereas it isn’t a frontrunner for corrosion safety, it stays our top-rated ethanol therapy and is provisionally really helpful for corrosion safety.

Star Tron Ethanol

Star Tron is made by Star brite, an organization that markets a variety of boat upkeep merchandise, a number of of which have earned high scores in Sensible Sailor exams. We beforehand examined Star Tron for its capability to delay or forestall phase-separation in ethanol fuels, and its capability to burn cleanly with out forsaking any ash residue. In that check, the product got here out with a Really useful score.

This time round, testers discovered that Star Tron helped inhibit corrosion, however it didn’t stand out as a high performer. Actually, Star Tron doesn’t declare to make use of corrosion inhibitors, however fairly focuses on retaining the system clear.

It helped, although lower than others, and we imagine it will carry out properly within the absence of seawater contamination. Star Tron is offered in 8-ounce, 16-ounce, 32-ounce, and 1-gallon bottles.

An emailed assertion from considered one of Star brite’s engineers (who Star brite prefers to maintain nameless) identified the worth of a “do no hurt” product within the tough environs of marine fuels: “When succinic acid, carboxylate acids, amine salts, and ester-based anti-corrosive components (that’s just about each additive available on the market) combine with sodium, they kind very sticky deposits. This kills Excessive Stress Frequent Rail diesels by sticking up the injectors. . . . Singularly stopping corrosion in seawater-contaminated fuel is vital, however treating the overwhelming majority of gasoline with pointless further anti-corrosive components (recall the refinery mix works tremendous for all however seawater-contaminated gasoline) is just not all the time the most effective reply.”

Backside line: Based mostly on this check and our 2009 check of ethanol components, this product is Really useful, though its corrosion prevention is just not as efficient as others within the check.

ValvTect Ethanol Gasoline Remedy

The ValvTect product delivered superb safety and in contrast favorably with the Greatest Selection Biobor. The one motive this was not named a “Greatest Selection” was its greater value. If you happen to use this product for different causes, there’s actually no motive to modify. It’s obtainable in 8- and 12-ounce bottles.

Backside line: ValvTect Ethanol was a high performer. It’s Really useful.

The Way forward for Gasoline Components

A bunch of producers and additive producers has fashioned a working group in cooperation with the Nationwide Marine Producers Affiliation (NMMA) with the intention of setting requirements for components, figuring out authorized merchandise, and checking out these they discover damaging. The working group has already decided that any additive that may droop or dissolve important quantities of water might be rejected. Engine producers we spoke with really helpful towards utilizing any alcohol-based merchandise akin to MDR E-Zorb that dissolve water in order that it could possibly be “cleanly burned” by means of the engine.


On the subject of corrosion prevention that can guarantee a protracted engine life, drier and fewer oxygen are greatest. We reiterate our recommendation to keep away from merchandise that droop water, which might result in extra corrosion-related carburetor clogging troubles as they assist distribute water and salt all through the gasoline system.

One other aspect within the gasoline safety chain is gas-tank filters, quickly to be phased into new boats with built-in gasoline tanks. We’re presently testing quite a lot of filters, and preliminary outcomes recommend that they might even be a useful in defending your gasoline system, however it’s nonetheless too early for us to know for sure.

We imagine that E-10 corrosion points ought to turn out to be much less vital as engine producers transfer away from alloys identified to be weak to E-10 and as fuel-dispensing gear at service station and gasoline docks is up to date. Particularly, zinc and Zamak die-cast components should be averted. Gasoline producers are additionally getting smarter about which corrosion inhibitors to make use of. We imagine we’re already seeing some enchancment.

Some components actually assist, stopping corrosion useless in its tracks. Others had no discernible impact. For year-round corrosion safety, we see a powerful case for utilizing Biobor EB, Mercury Quickstor, Sea Foam, or ValvTect Ethanol.

Best fuel additive for horsepower for your needs? You are at the right place. We recognize that amidst so many choices in the market, it can be perplexing and confusing to make the right pick.

Source: https://www.practical-sailor.com/systems-propulsion/outboards/e-10-fuel-additives-that-fight-corrosion

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