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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

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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.

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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.

Author: David Fuller

David Fuller is OnAllCylinders' managing editor. During his 20-year career in the auto industry, he has covered a variety of races, shows, and industry events and has authored articles for multiple magazines. He has also partnered with mainstream and trade publications on a wide range of editorial projects. In 2012, he helped establish OnAllCylinders, where he enjoys covering all facets of hot rodding and racing.