Metallic substances that are degraded by E85 include: zinc, brass, aluminum, and lead-plated steel. Alloys containing these metals must be individually investigated to determine their E85 compatibility. For example, lead-tin alloy is not E85 compatible. Unfortunately, many vehicles use aluminum in the fuel delivery systems to save weight, including in the fuel pump, lines, fuel rail, and fuel pressure regulator. Fuel also often is allowed to contact the aluminum block of many two-stroke engines. Furthermore, older vehicles often use lead-plated steel for the vehicle fuel storage tanks. These materials will react with E85, partially dissolving in the fuel. This can contaminate the fuel system, leading to clogged fuel filters and injectors, which in turn, cause poor vehicle drivability. Aluminum can be safely used if it is hard anodized or nickel plated. Most FFVs use hard anodized aluminum for the fuel delivery systems. Also, most modern vehicles use fuel storage tanks that are made of polymer compounds (which are resistant to E85) instead of lead-plated steel; thus, this problem is only a factor in older vehicles.

Other metallic compounds that are resistant to E85 include: unplated steel, stainless steel, black iron, and bronze. These materials can be substituted for the other compounds as required.