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The Ethanol Effect: Understanding Ethanol & What You Can Do to Protect Your Ride During Storage


Internal carburetor corrosion and damage caused by ethanol blended fuel. Image courtesy of Driven Racing Oil.

The U.S. Environmental Protection Agency seems to love its ethanol. Farmers love it, too.

But if you’re a hot rodder–particularly a hot rodder with a carbureted or older-style fuel system–ethanol isn’t exactly your friend. Ethanol blends can corrode your carburetor, fuel tank, and other fuel system components and damage engine seals and O-rings, according to industry experts. And that means costly repairs at the very least–and engine damage at worst. We saw this firsthand when a friend installed a new fuel pump on his 1949 Chevrolet pickup, only to have to replace that barely used fuel pump after the truck sat for an extended period.

To combat the problem, aftermarket manufacturers have developed several different types of fuel additives to protect older style vehicles from the negative effects of E10 and E15 ethanol blends. Since there are so many options available, the trick is knowing what to look for in these additives and understanding what makes them most effective. With hot rod/muscle car storage season coming up (at least here in the Midwestern United States), we reached out to a couple industry experts to get their opinions on what makes a good fuel additive for ethanol protection.

First, let’s look at the root of the problem.

The Ethanol Problem

Ethanol is found in 95 percent of gasoline in the United States. Typical ethanol fuel formulations are E10 (10 percent ethanol and 90 percent gasoline) and E15 (15 percent ethanol), which is steadily gaining momentum in some states. Ethanol is lauded by some for being a clean-burning, renewable fuel.

Sounds great, right?

The problem for hot rod enthusiasts and owners of older cars is that ethanol is hygroscopic, which means it absorbs water. Ethanol-blended fuel will naturally hold 0.5 percent water in suspension, but once the water content exceeds this percentage, the water/ethanol mix becomes heavier than the gasoline portion of the fuel. This leads to what experts call “phase separation,” which is the point at which the water/ethanol mix drops out of suspension and sinks to the bottom of the fuel tank. This can lead to a variety of problems, including the corrosion problem our friend experienced.

Because the fuel pickup is located on the bottom of the tank, the layer of water/ethanol mix is also often the first thing to get sucked up when the engine is cranked over. That means the corrosive mixture is circulated through your fuel system and into the engine, leading to possible corrosion of your fuel pump and other components. Although ethanol has been known to gum up and cause clogging in fuel injectors and fuel filters, the corrosion problem is typically limited to carbureted engines, according to Scott Diehl, National Sales Manager at Driven Racing Oil.

“Ethanol in a modern fuel-injected vehicle is typically not a problem,” he said. “The components used in these engines are more compatible, but carburetors are typically made from alloys that are more susceptible to corrosion–zinc, aluminum, and brass.”

According to Ed Callis, V.P., Technology at Red Line Synthetic Oil, other components are at risk, too.

Fuel hoses, O-rings, seals commonly installed in older engines and fuel systems are negatively affected by ethanol,” Callis said. “Leakage can result, so these components should be changed out with ethanol-resistant components.”

Callis says the makeup of ethanol-blended fuels can lead to more problems and potential engine damage down the road as well.

“Other than the possible elastomer compatibility problems, which I feel should be the most serious concern of older car owners using E10, an additional issue is the extra oxygen present in E10,” he said. “Since older engines lack the computer control and oxygen sensors of newer cars, adjustments are not made to fuel flow rates based on exhaust emissions. Knock sensors were also not generally installed in older engines, and the higher air/fuel ratio caused by oxygen present in E10 can cause a leaner-running engine. That can produce more heat as well as poorer fuel economy.”

How to Protect Against the Effects of Ethanol


Red Line’s fuel system treatment is formulated to remove excess water from ethanol-blended fuels.

The optimal solution is to not use ethanol in an older vehicle. However, since 95 percent of all gasoline contains some level of ethanol, that can be a huge hassle and expense. Many aftermarket companies offer fuel additives to combat the effects of ethanol, but Diehl and Callis both caution you to do your homework.

“The fuel stabilizer market is relatively unregulated and lacks an industry specification to assist the consumer in selecting a product that is truly effective and whose performance goes beyond just words on a label,” Callis said. “The NMMA (National Marine Manufacturers’ Association) is working on a specification for fuel additives that addresses these primary performance parameters: stability against oxidation (storage life), corrosion protection, combustion deposits control, and water handling.”

Companies like Driven Racing Oil, Red Line, and Star brite all warn their customers to be wary of alcohol-based additives.

“A lot of times, companies will use alcohol in their additives,” Diehl said. “This is a bad idea because it can change the makeup of the gasoline.”

Callis also cautions against additives that are high in alcohol.

“”What many people do not realize is that all fuel sold in the USA contains additives,” he said. “Oxidation stability, corrosion protection and engine-deposits control are addressed in an ASTM spec for motor fuel sold in the USA. The EPA sets the minimum amount of deposit control additive required in motor gasoline because of the significant negative effect of engine deposits on exhaust emissions. Request an MSDS for any product you might be considering purchasing and look in the contents section for any alcohols or butyl cellosolve. If those types of components are present at levels above 10 percent, avoid those products.”

Driven Racing Oil's Carb Defender helps prevent corrosion and gummy deposits.

Driven Racing Oil’s Carb Defender helps prevent corrosion and gummy deposits.

For its part, Diehl says Driven Racing Oil products are strictly corrosion inhibitors designed to prevent any damage or performance-robbing deposits to mechanical components.

“Our product doesn’t affect the makeup of the fuel,” Diehl said. “It is a corrosion and rust inhibitor, and the fuel simply acts as a carrier to take it through the fuel system. It does not eliminate moisture but simply protects components from the effects of moisture and acts as fuel preservative during long storage periods. It also cleans deposits which can build up during normal operation and have an adverse effect on performance.”

Other companies offer formulas they claim will help eliminate excess moisture in ethanol blends. Star brite, for example, says its Star Tron additive uses a special enzyme formula that reduces the water droplet size throughout the fuel. This allows more of the water to be burned off as the engine operates and prevents water build-up from reaching levels that create phase separation.

Red Line’s Callis believes consumers should choose products that adhere to those four NMMA standards.


Star brite’s Star Tron Enzyme fuel treatment.

“As one of the formulators of the NMMA spec, I believe strongly in their four performance parameters being the key features to look for when choosing a fuel additive,” he said. Red Line fuel additives are performance based, not marketing hyped, as are all Red Line products.”

In addition to being picky about the additives you use for ethanol-blended fuel, there are some other tips you can use to prevent ethanol damage to your engine and fuel system. Callis offered up this advice:

  • Buy fuel from a busy gas station–higher throughput ensures that fuel in their storage tanks in fresher.
  • If you store fuel in portable containers, make sure you keep the cans in a relatively cool, dry area and keep them sealed. If you intend to store fuel, either in a container or in the vehicle fuel tank for more than a month or two, add a fuel stabilizer.
  • If you intend to store gasoline in a vehicle tank for an extended period of time, top off the tank.

Love it or hate it, ethanol isn’t going away. By using the right additive and following the tips above, your engine and fuel system will be around for long time, too.

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  1. wayne glasgow says:

    You guys should do some more research be for publishing something some irrisponsible. Ethanol is 100% non corrosive. I have been running ethanol for well over 15 years now without ever having any problems with corrosion. It does not eat rubber or aluminum in fact I have it stored in several aluminum tanks and have for years. I also have a car with 98% ethanol in it that has sat for the past 4 years untouched and the system is just fine in fact all rubber is still like brand new! The only problem with putting it in your street cars is that it cleans the fuel system and what you are left with is all the nasty crap in gasoline in the form of deposits in your fuel filters and carbs. What you guys are describing is METHANOL!

    • OnAllCylinders says:

      Mr. Glasgow. We appreciate your feedback. As mentioned in the post, ethanol itself is non-corrosive but it does absorb water, which creates a corrosive mix, especially when it drops out of suspension. Many race cars are set up to run ethanol and have no problems, but in older, carbureted street cars it can be a problem— as we witnessed first hand. We are very confident in our research and sources.

      • Doc Adam Caldwell says:

        OnAllCylinders Keep up the excellent work.

      • Nicholas Rice says:

        So water is the problem and Or improper storage. Vehicles with vented caps allow the humid air into the gas tanks and the water will condense on the walls which will run down into the fuel. The Ethanol is NOT pulling water out of the Air. If the Ethanol was not in the fuel the water would still be in the tank. And it would still settle to the bottom as it will not mix with the gas. Still forming a water layer to be sucked up into everything. The Ethanol is actually helping things. It makes water combustible. The more Ethanol in the fuel the more that can be absorbed without Phase separation or corrosion. Water getting into the fuel system is the enemy no Ethanol. Fill your tank with E85 before storing it leaving the tank full. so there is no room for air to get in there for no water. Would you see the same phase separation or corrosion issues? Definitely not.

        • Bill Reed says:

          It is a problem. For you, it may be that you get ethanol that has not been exposed. If you ask your distributor or if you get it locally, then chance no water. It can cause valve problems depending on the process of getting the “gas” to the pump. When exposed to air brings water. It is lower in combustion value by as much as 30%! Are you a corn producer or rely on farmers? I am just a consumer. Is your car newer, that can make a difference. I have older cars. It is not worth the lower mileage. I get about 5% less gas mileage. I will be going to an all unleaded station from here on. NO, we are describing Ethanol. Bad stuff for my cars. Government was never truthful about it. This is what happens when government regulates.

      • Yup, my old 77 Chevy Van is prof of exactly what you guys are talking about. I drive it to Texas every winter, 4000 miles return. Everything you talked about has and is happening to my old ride. I’ve been through a one gas tank, plus a couple carbs. Not to mention all other shit like fuel hose, etc…

    • John Boitano says:

      I had a rusty tank issue after one winter in storage. I didn’t expect it to happen but it did happen. Now I safeguard my vehicles by using ethanol free fuel for storage. There is a reason marina’s here in the pacific nw don’t sell ethanol fuel at all. It causes lots of issues in boats.

    • Doc Adam Caldwell says:

      Wayne Gasgow please get an education before replying for the ethanol industry. All of your statements are proven false. Time and Time again you pro ethanol crowd copy and paste and do not even understand the facts.

    • Seymour buts says:

      You sir are a moron…

    • Next article you comment on, you might want to read it! Just sayin’…

    • its corrodes, hence why it is only recommended for some systems which are stainless lines, valves to run full e85. so this e10 shit just does not corrode as bad, but it will

    • Phil Turchen says:

      Thank you for your support on this topic. I am a producer of ethanol in Colorado.

    • Bill Reed says:

      It is a problem. For you, it may be that you get ethanol that has not been exposed. If you ask your distributor or if you get it locally, then chance no water. It can cause valve problems depending on the process of getting the “gas” to the pump. When exposed to air brings water. It is lower in combustion value by as much as 30%! Are you a corn producer or rely on farmers? I am just a consumer. Is your car newer, that can make a difference. I have older cars. It is not worth the lower mileage. I get about 5% less gas mileage. I will be going to an all unleaded station from here on. NO, we are describing Ethanol. Bad stuff for my cars. Government was never truthful about it. This is what happens when government regulates.

  2. Great article. I live in Florida, where I can get ethanol-free gas, but have seen first-hand the problems that those who have older cars have had with it. And E10, in my experience, gets 10-15% worse mpg than E-free gas…where are the savings, environmental and otherwise, there? We can thank the politicians and corn producers for foisting this boondoggle on us…ethanol is great in engines designed for it, but what 99% of us drive was designed to operate best on gasoline. I drive a Flex-Fuel Toyota Tundra, which can handle E85. Toyota calls for a 100% synthetic oil change in its 5.7-liter V8 in a non-flex-fuel vehicle every 10,000 miles. In my flex-fuel truck, it’s 5,000 miles. Read the fine print in my owner’s manual, and if I use E85 more than half the time, I’m supposed to change the oil every 2,500 miles. Toyota isn’t stupid. There’s a reason for all that. And yes, I fill it with E-free fuel whenever I can.

  3. It takes a gallon of fossil fuel to make a gallon of ethanol. Why do we not go back to using corn for food?

    Recently produced cars handle it well but my 2 cars are low mileage and 10 years old. 15% drop in mileage.

    • The bigger resource that most E People do not want to talk about is the 6 gallons of water that are poluted non recoverable that are used in the making of their beloved corn juice! It has no caloric value so it does not improve anything as far as MPG or HP… it simple extends .9 of a gallon into 1.0 gallons at great expense to the American tax payer… as a hand out to the farmer…

      get the facts and boycot this corn juice crap!

      • Nicholas Rice says:

        James it takes 44 gallons of water to refine 1 gallon of crude. One barrel of crude makes 22 barrels of ethanol. Here at our ethanol plant we use 2.5 gallons of water to make one gallon of ethanol and that water is leaving as clean steam to the atmosphere which will in turn rain back down on the corn. We also make 2.85 BTU worth of energy for every 1 BTU worth of energy we use. And that includes planting the crop, harvesting the crop bring the crop to the facility and also trucking the fuel to its final destination. Ford says that my F150 gains 15HP and 10FPT just by running on E85 or regular unleaded. And here in michigan you can find it for 60cents less than regular unleaded all over the state. so the savings is about 2-3cents every mile. If a vehicle was designed to run on only e85 you could take a 4 cylinder direct injected, turbo charged engine coupled with high compression and make the same power and torque as the diesel engine in a UPS sized truck and get better fuel economy with the same power in an engine a third of the size.

    • Phil Turchen says:

      Steve – I seriously doubt you are seeing a 15% drop in MPG’s! The corn that we use in the ethanol industry is cattle corn and only cattle corn. The infrastructure is not there to supply sweet corn nor would we ever use it. The model works all day long. We take a corn that otherwise would have gone directly to cattle. Grind it, cook it, ferment and distill it. The co-products that come from it are really something to be proud of. We get WDGS (wet distillers grains & solubles), CO2 that is captured, compressed and sold to beverage companies for carbonation. Corn syrup which is an additional feed product for cattle. Corn oil which can be sold to the cattle industry or turned into bio-diesel. All of this from a crop that is grown every year. We as a country (USA) are still the #1 exporter of corn in the world.

    • Don’tmournthehorshoemaker says:

      First of all- That’s not how energy works at all in this case. If you follow Newton’s 3rd law or consider how this stuff is mass produced at SELF SUSTAINING ethanol refineries you can see they don’t burn any fossil fuels. The photosynthesis process is enough to power these facilities by just using the excess biomass produced during the crop production.

      • Don’tmournthehorseshoemaker says:

        To further iterate- There is some extreme bias going on here or oil industry false information as has been happening since ethanol was introduced in the Rockefeller era. Or we can use leaded fuel as an example. Or perhaps OSHA and the wars being fought in the Middle East. Our involvement in Afghanistan/vs Russia or perhaps Iraq VS Iran. If you have ever been to Kuwait (I have. Marine 02-06) and have seen the massive amount of refineries you’d know why we are helping them and not some disparaged country in Africa.

  4. There’s a reason it is all but impossible to buy a new, “ordinary” mechanical fuel pump for older applications that is warranted more than one measly year.

    I’ve had to buy new, standard mechanical fuel pumps for both my 1973 Mustang and 1971 Barracuda in the last three years. While they work well, they only have [had] a 12-month warranty in an age when so many all-new components have lifetime warranties.

    ‘Can’t help but think that the manufacturers know what they will be pumping and don’t want to keep furnishing hobbyists new fuel pumps every three or four years for cars that are infrequently driven…and I’ve Sta-Bil religiously, forever; ‘now using the new formulations that are supposed to help ameliorate the bad effects of alcohol-enhanced gasoline.

    OTOH, I am fortunate enough to live in a market (Indianapolis) where 91-octane, alcohol-free gasoline is marketed at a handful of (but not many) CountryMark Co-Op gas stations, one of which is an easy 23-mile round trip from my house.

    Bob Palma

    • I know this is an old post..
      The US was the best Country, we had the best of everything, our Politicians sold us down the river.. I believe in the EPA, but it has to be worldwide or it does not work..damn spacebar.. tired of good old USA sending stuff overseas, and buying from overseas, we need to get out of the Damn world ecomony.We in the usa can shutdown the whole world,if our people would stick together, because we grow most of the food for the world.. shut it down, and watch what happens, .99 gas again, cost of living where it should be.. Yhese damn Countries we are “Helping”, do not want us on their Land..

  5. my new 2015 f350 is designed to run on ethanol

    • Rick VanDeBogart says:

      Yes, it is designed to run on the ethanol blend but if you store or let your vehicle set for two or three months with E-10 or E-15 fuel in the lines, tank or in your carbs the fuel will take on the moisture in the air and then the gasoline and water separate into a sludge that can fowl your lines and carbs. Fuel injected motors are usually ok!

  6. gene johnson says:

    obviously Mr. Glasgow hasn’t seen what this stuff does to small engines either, i work in this industry and it is THE biggest problem with this type of equipment-maybe ethanol fuel doesn’t harm bicycles?

    • Nicholas Rice says:

      I use Only e15 in my cub cadet zero turn as well as my 2 stihl chainsaws and have never had one single issue. Granted i to properly store mine and make sure i never leave fuel to go stale. Now why is it that i never in the past 10 years have had this issue? Ever. Is it the fuel or is it improper storage? Water getting into your fuel is the problem. Not the Ethanol.

  7. Rick VanDeBogart says:

    This same situation happens in lawn mowers, chain saws, and lawn equipment. The hardening of the remains E10 or E15 solidify in gas tanks, fuel lines, and carbs so run and drain all gass out of your power equipment!

    • if I store a small engine I find bit of fuel line and boat primer bulb, push diesel through system, when it needs to be started, same setup but with fresh fuel, starts everytime, found if I do nothing, blocked jets needles stick etc

  8. Bruno Brandenburg says:

    Imagine here in Brazil than gasoline has 25% ethanol, we can protect our old cars here with few changes

  9. Brownishbear says:

    I have a ’71 Dodge Polara that I like to drive regularly, but the ethanol is eating up all the rubber. No signs of corrosion yet, but I’ve already had to replace the lines going to and from the tank, as well as the filler neck grommet. Accelerator pump just started giving me trouble too. I can’t find a different material for the grommet-what do you guys recommend to combat that problem? Where can I custom order one or make one from?

  10. One thing you neglected to mention is the drop in octane level in gasoline part of the mix when the ethanol separates from the mixture. https://www.youtube.com/watch?v=ceW9Nc1hVHU#t=184

  11. Amazing what people say to see their own additives

  12. Marc Rauch says:

    This is another idiotic article written about ethanol by someone who should know better. The author (David Fuller) criticizes ethanol by saying that ethanol will only “absorb” so much water, and that after that level the water falls to the bottom of the fuel tank and it causes problems. There’s two very incorrect points here. The first is that ethanol doesn’t “absorb” water, it break the water molecules down and allows the combustion process to take place. While some people use the word “absorb” to casually describe the process, other people have taken on the word to mean something different and then invent other nonsense.

    The other nonsense is the second part of the incorrect statement. Yes, there can be a point at which there is too much water for the ethanol to effectively breakdown, however gasoline has no ability to breakdown water at all. This is why ethanol (Dry Gas) has been used for decades in leaded-gasoline and gasoline with MTBE to remove water that forms in the fuel tank. So to criticize ethanol for doing what motorists have needed to be done is ludicrous. Phase-separation doesn’t occur because of ethanol, it’s occurs because gasoline has no ability to breakdown the water and expel the water molecules in the combustion/exhaust process.

    There are only two ways to get water out of your fuel tank: drain it, or add ethanol.

    There are some products that don’t contain ethanol but emulate the “drying” ability of ethanol. These are some of the products pitched later in the article. But the ingredients used are simply formulated to mimic ethanol. These ingredients are not better than ethanol, they are typically other types of alcohols or chemical formulas created from petroleum oil (not all alcohols are ethanol). This is why the oil industry favors these products, because they give more profits to the foreign dominated petroleum oil industry.

    As for the claims made by these other products, Mercury Marine (one of the world’s largest manufacturer of boat engines) calls these claims false and says that there is no product that will cure the so-called problems caused by ethanol. The reason why Mercury’s comments on this issue is so important is that open venting system used in marine engines allows for more water moisture to form.

    Water moisture forms in fuel tanks is because of condensation. Opponents of ethanol will claim that it’s because ethanol is hygroscopic and sucks the moisture out of the air, but that’s just another anti-ethanol myth.

    If you want to sell engine treatment products do it because there is a benefit, not based upon snake-oil salesman lies.

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  14. Ethanol cleans out the water,rust etc in the tank and can plug the filters in old engines. Fuel injectors can also be plugged if the junk cleaned from the tank is bad enough. Don’t get E-85 and 10-15 per cent blends confused. EPA requires a blend in gas for the Phoenix area. It helps to
    Clean our air. I drive a 95 Cadilac here and it sits with a tank of fuel all summer. NO PROBLEM!! It does not cause a food shortage. Only the sugar is used, the protein is used for cattle feed and can be
    fed wet so not to cost to dry. Ethanol is good for the and should not be confused with the cost of food!

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  18. The problem is not so much the corrosion problem is the degradation of the non resistant seals in the carburetor. That’s the real issue with ethanol based fuels. The epa should have done due diligence with their scientific research and realized that the emissions numbers were not working, and left the fuel alone.

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  20. Bert Blpock says:

    Are there newer types of seals and other components made for the older carburetors? A carb kit could have these newer ethanol resistant materials and then the problem would be solved – no? Please comment.

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