is non ethanol gas bad for your car

[VanAmir]

No, non-ethanol gasoline is not bad for your car; in fact, it's often better for certain vehicles and for long-term storage. The primary benefit of ethanol-free fuel is its stability and reduced affinity for water absorption, which minimizes the risk of phase separation—a condition where ethanol-blended fuel absorbs water and can separate, potentially causing engine damage. For classic cars, boats, small engines (like lawnmowers), and any vehicle sitting unused for months, non-ethanol gas is the superior choice to prevent fuel system corrosion and clogging.

However, for most modern cars designed after 2001, using gasoline with up to 10% ethanol (E10) is perfectly safe and often more readily available and cheaper. These vehicles have fuel system components engineered to handle ethanol's properties. The key is to follow your owner's manual. Using a higher-octane fuel than recommended does not provide a performance or efficiency benefit for most standard engines.

The following table compares key characteristics:

Feature	Ethanol-Free Gasoline	E10 Gasoline (10% Ethanol)
Energy Content	Higher; more energy per gallon, potentially leading to slightly better fuel economy.	Lower; ethanol contains less energy, which can result in a 3-4% reduction in MPG.
Stability & Shelf Life	Excellent; can be stored for 6+ months without significant degradation.	Poor; prone to phase separation and oxidation within 3 months, especially in humid conditions.
Water Absorption	Low; less likely to cause corrosion in fuel systems.	High; ethanol acts as a solvent and can absorb water, leading to potential corrosion.
Octane Rating	Typically available in high octane grades (91-94).	Available in all octane grades (87, 89, 91).
Cost	Generally more expensive per gallon.	Typically the most affordable and common option.
Best For	Classic cars, boats, small engines, seasonal equipment, and long-term storage.	Most modern vehicles designed for E10, daily drivers.

Ultimately, the best fuel for your car is the one specified by the manufacturer. If you own equipment that is used infrequently, the extra cost for non-ethanol gas is a worthwhile investment to avoid costly repairs.

[DelGrace]

As someone who restores old motorcycles, I only use non-ethanol gas. Ethanol is brutal on rubber seals and gaskets in older fuel systems, causing them to dry out and crack. It’s also less stable. If a bike sits for a few months with E10, the fuel can go bad and clog the tiny jets in the carburetor. For anything vintage or with a small engine, ethanol-free is cheap insurance. For a new car? You’re fine with regular.

[AllisonDella]

Think of it from a chemistry perspective. Ethanol attracts water from the air, which can lead to corrosion inside your fuel tank and lines. This is called phase separation. Non-ethanol gas doesn't have this issue, making it more stable. For your daily driver that burns through a tank quickly, it's less of a concern. But for anything you don't use often—like a lawn tractor, generator, or sports car—the stability of ethanol-free fuel prevents starting issues and protects the entire fuel system.