Can E15 gas damage your engine? – Jalopnik

Although gas stations are required to display warning labels stating the ethanol percentage of the fuel, you may or may not have noticed it, especially if it is missing or unclear. For those who don’t know, E15 gas is typically unleaded 88 and contains up to 15% alcohol, which is slightly higher than regular 87 pump gas which contains up to 10% ethanol. Check out our overview if you’re wondering why gasoline contains ethanol and how it affects your engine.

Whether E15 will damage your engine largely depends on the age and model year of the vehicle. According to the EPAE15 gas is approved for use in passenger cars (model year 2001 and later), as well as flex fuel-capable cars. As you can see, pre-2001 cars and trucks do not necessarily meet the E15 standard. Filling these vehicles with E15 can cause numerous problems, including fueling problems, corrosion, improper combustion, high cylinder temperatures and damaged rubber parts. You may even notice a loss of power, along with starting problems and clogged fuel filters.

It’s also worth pointing out that, according to the EPA, E15 should not be used in lawn mowers, motorcycles, chainsaws, and boats. In addition, heavy-duty engines used in vans and school buses are also not allowed to use E15. But why, you ask? Cars and trucks that are E15 compliant have upgraded components and other hardware modifications. But more importantly, the sensors and computers inside are programmed to adjust fuel parameters and ignition timing to compensate for the high oxygen levels of the ethanol mixture.

Filling up with E15 does not ruin your car overnight. Let’s just say it’s not as bad as putting diesel in a gasoline car. Ethanol, a form of alcohol, burns at a higher temperature than gasoline. It is not uncommon for old carbureted engines to run lean after using E15, especially in the case of engines that are not computer heavy. As you may know, this can cause the engine to experience pre-ignition or detonation. Furthermore, a research paper published by the National Renewable Energy LaboratoryOlder engines not equipped with hardened valve seats showed long-term wear after running on E15.

Ethanol is more corrosive than gasoline, so fuel hoses, seals and gaskets from incompatible engines will also be reluctant to use E15. Perhaps the biggest problem with ethanol is its affinity for absorbing water. The hygroscopic nature of ethanol not only causes corrosion, but can also lead to other problems, especially during storage. Understand that ethanol can literally pull water vapor from the surrounding air, leading to phase separation, meaning gasoline floats above water in the fuel tank.

Something else to consider is vapor lock. Because ethanol is more volatile than gasoline, these vaporized molecules (usually from excess heat) can prevent the fuel system from sending the necessary amount of fuel to the engine. In addition, the octane number of the fuel is reduced as ethanol evaporates. Gasoline can spoil if left in your car long enough, and it can also lose so much octane that the engine can even be difficult to start. Basically, if the owner’s manual says E15 is OK, then it’s fine to use, but don’t experiment.