Should I use ethanol gas in my car?

Generally yes—with caveats. E10 (up to 10% ethanol) is safe for virtually all gasoline cars, E15 (15% ethanol, often labeled “Unleaded 88”) is approved by the U.S. EPA for 2001 and newer light-duty vehicles but should be used only if your automaker allows it, and E85 (51–83% ethanol) should be used only in flex-fuel vehicles. Expect slightly lower fuel economy with higher ethanol blends; choose based on your vehicle’s compatibility, local rules, and cost per mile.

What ethanol-blended gasoline means for everyday drivers

Ethanol is an alcohol added to gasoline to increase octane and reduce certain tailpipe emissions. The blend you choose affects compatibility, performance, fuel economy, and price—so it’s important to know what the labels mean and what your vehicle is designed to handle.

• E0: Pure gasoline. Highest energy per gallon, often costs more, popular for small engines and marine use.
• E10: Up to 10% ethanol. The de facto standard in many markets; compatible with essentially all gasoline cars and light trucks.
• E15 (“Unleaded 88” in the U.S.): 15% ethanol, 88 AKI octane. EPA-approved for 2001+ light-duty gasoline vehicles; compatibility still depends on your automaker and local regulations.
• E85: Typically 51–83% ethanol (seasonal variability), >100 octane. Use only in flex-fuel vehicles (FFVs). Non-FFVs can be damaged or run poorly on E85.

Knowing the blend helps you balance cost, efficiency, and compliance. When in doubt, E10 is the safe default for gasoline vehicles; E85 is exclusively for FFVs.

How to decide what to pump

The following steps help you determine whether ethanol gas is appropriate for your car and which blend to choose.

1. Check the owner’s manual, fuel door sticker, or gas cap: Look for specific approval of E15 and, if applicable, E85. Many 2012+ U.S. models allow E15; all FFVs allow E85.
2. Verify local labeling and rules: In the U.S., E15 is commonly labeled “Unleaded 88.” Seasonal and state rules can affect availability; check pump labels and any posted restrictions.
3. Do the cost-per-mile math: Ethanol blends usually cost less per gallon but deliver fewer miles per gallon. See the quick guide below to estimate your break-even.
4. Match fuel to engine type: Use only E0 or E10 in small engines (mowers, chainsaws), boats, and many powersports machines; avoid E15/E85 unless the equipment explicitly allows it.
5. Consider your use case: Daily commuting favors convenience and price per mile; long-term storage, marine use, or vintage vehicles may benefit from ethanol-free fuel.

These steps ensure you protect your engine and wallet while staying compliant with manufacturer recommendations and local rules.

Pros and cons of ethanol-blended gasoline

Ethanol blends offer trade-offs that vary by vehicle and driving pattern. The points below summarize what most drivers can expect.

• Pros:
  

  • Higher octane per dollar: Ethanol raises octane; E15 (88 AKI) is slightly higher octane than regular 87, often at a lower price point.
  • Cleaner combustion of certain pollutants: Typically reduces carbon monoxide and some aromatics compared with straight gasoline.
  • Domestic and renewable content: Increases fuel supply diversity in markets like the U.S.

• Cons:
  

  • Lower energy content: Expect about 3% fewer MPG with E10, around 4–5% fewer with E15, and roughly 25–30% fewer with E85 versus E0.
  • Compatibility limits: E15 not approved for older vehicles and many small engines; E85 requires a flex-fuel vehicle.
  • Storage sensitivity: Ethanol absorbs moisture; not ideal for long storage in equipment or boats without stabilizer and proper practices.

For most modern gasoline cars, the benefits of E10 and, where approved, E15 can outweigh the drawbacks. The key is matching the blend to your vehicle and usage.

Cost-per-mile: a quick guide

To decide if a higher-ethanol blend saves money, compare cost per mile, not just price per gallon. Use your current price and expected MPG change to estimate the break-even.

• E10 vs E0: If E10 is at least ~3% cheaper per gallon than E0, cost per mile is roughly a wash.
• E15 vs E10: E15 typically brings an extra ~1–2% MPG drop compared with E10. If E15 is ~2% cheaper per gallon than E10, it likely breaks even or better.
• E85 vs E10: Expect ~25–30% lower MPG. E85 must be at least ~25–30% cheaper per gallon than E10 to be cost-neutral on a per-mile basis.

Real-world results vary by vehicle and driving conditions, so consider tracking a couple of fill-ups to validate your actual cost per mile.

Compatibility and warranty considerations

Using a fuel blend your vehicle isn’t designed for can trigger drivability issues and jeopardize warranty coverage. Here’s what to check and why it matters.

• EPA approvals: In the U.S., E10 is approved for all gasoline vehicles; E15 is approved for 2001+ light-duty vehicles but still subject to automaker and state rules.
• Automaker policies: Many manufacturers approve E15 for late-model vehicles; consult your owner’s manual or fuel-door label for definitive guidance.
• Flex-fuel vehicles (FFVs): Identified by yellow gas caps, “FFV” badges, or specific VIN codes. Only FFVs should use E85.
• Small engines and marine equipment: Typically limited to E10 max; E15/E85 can cause damage or unsafe operation.
• Premium-required engines: E15’s higher octane (88 AKI) does not substitute for premium (91+ AKI) where required.

Confirming compatibility before you fill up is the simplest way to avoid performance issues and potential warranty disputes.

Performance, emissions, and drivability

Ethanol’s high octane can support knock resistance, but its lower energy content affects efficiency. For most modern vehicles, engine controls seamlessly adapt within approved blends.

• Octane and power: Higher ethanol blends raise octane; some engines may benefit marginally under high load, but many drivers won’t notice a power difference.
• Fuel economy: Expect small MPG decreases as ethanol content rises, most noticeable with E85.
• Cold weather: E85 can be harder to start in extreme cold; suppliers often use winter-grade blends (e.g., E70) to improve starts.
• Emissions: Ethanol reduces certain pollutants at the tailpipe; lifecycle greenhouse gas impacts vary by production methods and logistics.

In ordinary driving, these factors are subtle with E10 and E15, but more pronounced with E85 unless the vehicle and tune are optimized for it.

Regional notes and availability

Fuel labels and policies vary by market, so check local practice before changing fuels.

• United States: E10 is common; E15 is often sold as “Unleaded 88.” Summer availability of E15 has sometimes required seasonal waivers—check current local rules and pump labels.
• Europe: E5 and E10 are common; E85 is available in select countries. Labels typically show the “E” number in a circle on the pump.
• Other markets: Consult national fuel standards and labeling; compatibility rules may differ.

Local labeling is your best guide at the pump. When unsure, choose the blend specifically listed as acceptable in your owner’s manual.

Practical tips for drivers

These simple practices help you get the most from ethanol-blended fuel while avoiding pitfalls.

• Read the label every time: Pumps can vary by station or season; confirm blend before fueling.
• Switching blends: It’s fine to move between E10 and E15 in compatible vehicles; mix within approved ranges.
• Storage and small engines: Use ethanol-free (E0) or E10 with stabilizer for equipment stored for months; avoid E15/E85 unless specified by the manufacturer.
• Monitor MPG and drivability: Track a couple of tanks when trying a new blend; stick with what works best for your car and budget.

Following these tips minimises risk and helps you make data-driven decisions about fuel choice.

Bottom line

If your gasoline car is 2001 or newer, E10 is a safe bet; E15 can be a good, cost-effective option if your automaker approves it and it’s available; E85 is only for flex-fuel vehicles. Expect modest MPG trade-offs and decide based on compatibility, local rules, and price per mile.

Summary

Use E10 in virtually any gasoline car; consider E15 (“Unleaded 88”) for 2001+ vehicles only if your manual or fuel-door label permits it; reserve E85 for flex-fuel vehicles. Ethanol blends lower per-gallon cost and raise octane but reduce MPG. Always verify pump labels and manufacturer guidance, and choose the blend that offers the best cost per mile without compromising compatibility or warranty coverage.

What is the downside of ethanol in gasoline?

Gasoline is not water soluble, but ethanol is. Therefore, ethanol can pick up contaminants that gasoline doesn’t and may deposit those contaminants inside your engine, leading to fouled filters or injectors. This can cause noticeable decreases in engine performance if not dealt with.

Do cars run better on ethanol free gas?

Yes, cars can run better on ethanol-free gasoline, which provides slightly better fuel mileage (around 3-4%) and can offer a slight increase in power due to ethanol’s lower energy content. Ethanol-free gas is particularly beneficial for older vehicles and small engines, such as those in classic cars, boats, lawnmowers, and chainsaws, as it is less corrosive and better for long-term storage. However, for most modern vehicles designed to handle E10 fuel (a 10% ethanol blend), the difference in performance may be minimal, and the higher cost of ethanol-free gas is often a deterrent. 
Benefits of Ethanol-Free Gas

• Improved Fuel Economy: Ethanol contains less energy than gasoline, meaning you get fewer miles per gallon with ethanol-blended fuels. 
• Increased Power: Pure gasoline provides more power than ethanol blends. 
• Engine Longevity: Ethanol can corrode fuel system components and attract water over time, so ethanol-free gas helps prevent this damage, especially in older or less tolerant engines. 
• Better Storage: Ethanol-free fuel can be stored for longer periods (up to six months) without degrading as quickly as ethanol-blended fuels. 

Considerations for Ethanol-Free Gas

• Cost: Ethanol-free gasoline typically costs more than conventional fuels. 
• Modern Vehicle Compatibility: While beneficial for certain engines, modern cars manufactured after 2011 are designed to run on E10 fuel, and the difference in performance might be too small to notice or worth the extra cost. 
• Availability: Ethanol-free gasoline is not as widely available as standard blended fuels. 

When to Use Ethanol-Free Gas

• Older Engines: Opens in new tabVehicles with carbureted engines, such as classic cars, often benefit from ethanol-free fuel. 
• Small Engines: Opens in new tabLawn mowers, leaf blowers, and chainsaws are excellent candidates for ethanol-free gas to prevent gumming and corrosion. 
• Marine Engines: Opens in new tabMany boat engines are not compatible with ethanol and require ethanol-free fuel to avoid damage. 

What cars should not use ethanol gas?

The EPA says E15 can be used in flexible-fuel vehicles, as well as 2001 and newer cars, light-duty trucks, and medium-duty SUVs. Don’t use E15 in motorcycles or other small engines, heavy-duty trucks, or nonroad vehicles such as boats and snowmobiles.

Should I put ethanol gas in my car?

Pure gas gets you slightly better gas mileage as ethanol has less btu’s per gallon. However it’s not worth the extra premium and the car requires 91. The car won’t care whether it has ethanol or not. Pretty much all cars are designed these days to handle at least 10% ethanol so it doesn’t really matter.