Bad Gas in Colorado: What It Is and How to Avoid It
Josh Gough • September 1, 2025
Bad Gas in Colorado: What It Is and How to Avoid It
We’ve all been there—you fill up at a gas station, get back on the road, and within a few miles your car starts running rough. Maybe it sputters at a stoplight, maybe your check engine light comes on, or maybe it just doesn’t have the same pep it usually does. Nine times out of ten, the culprit is bad fuel—what we call “bad gas.”
So, what’s bad gas?
“Bad gas” isn’t just one thing—it’s a catch-all for gasoline that’s either contaminated, old, or mixed wrong.
Here are the most common reasons:
- Water got in the tank (from condensation, rain leaks, or poor station maintenance).
- Sediment and dirt at the bottom of the station’s tank got pumped into your car.
- Old gas that sat too long before being sold.
- Wrong blend of fuel—in Colorado, we switch between summer and winter gas, and if a station messes that up, your car feels it.
Signs you might have filled up with bad gas
- Rough idling (your car shakes when stopped).
- Hesitation when you press the gas.
- Stalling right after starting.
- Worse gas mileage than usual.
- That lovely check engine light.
Why this happens more in Colorado
Colorado isn’t just high altitude—it’s also got big swings in weather. That means:
- Ethanol blends (E10) are common, and ethanol loves to pull in water.
- Freeze-thaw cycles can cause condensation and water buildup.
- Altitude fuel blends are different from sea level, so stations need to stay on top of seasonal switches.
What to do if you get bad gas
- Don’t keep driving if it runs really rough. You could cause bigger problems.
- Save your receipt. It’s your proof if you need to file a complaint.
- Report it. In Colorado, you can contact the Department of Agriculture (they test fuel quality).
- Get it checked. A shop can test, drain, and replace the fuel if needed.
- Stick to busy, reputable gas stations. The more turnover they have, the fresher the gas.
Pro tips to avoid bad gas
- Skip filling up right after the tanker truck delivers fuel—sediment gets stirred up.
- In winter, don’t let your tank run too low (less air = less condensation).
- If your car says “premium required,” don’t cheap out—altitude doesn’t change that.
- Once in a while, run a fuel system cleaner, especially if you always use E10.
👉 Bottom line: Bad gas happens, but you can minimize the risk. If your car starts acting up right after a fill-up, don’t ignore it—deal with it before it turns into a bigger (and more expensive) repair.
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How to Prepare Your Vehicle for Colorado Winters As winter approaches in Colorado, it's crucial to ensure your vehicle is ready to handle the harsh conditions. Snow, ice, and frigid temperatures can take a toll on your car, but with proper preparation, you can stay safe and keep your vehicle running smoothly. Here’s how to winterize your vehicle for Colorado’s unpredictable winters. 1. Check Your Battery Cold temperatures can significantly reduce your battery’s power, making it harder to start your engine. Have your battery tested to ensure it’s in good condition, and replace it if necessary. Clean any corrosion from the terminals and ensure all connections are tight. 2. Inspect Your Tires Traction is key when driving on icy and snowy roads. Check your tire tread depth—if it’s below 4/32 of an inch, consider replacing your tires. Investing in winter tires designed for icy conditions can provide better grip and improve your safety. Also, make sure your tire pressure is at the recommended level, as it can drop in cold weather. 3. Check Your Fluids Antifreeze : Ensure your coolant is at the right mixture to prevent freezing. Oil : Consider using a winter-grade oil that flows better in lower temperatures. Washer Fluid : Use a winter-specific washer fluid that won’t freeze in cold temperatures. 4. Inspect Your Brakes Your braking system is critical in winter driving conditions. Have your brakes inspected to ensure they’re in good working order, and replace worn brake pads if needed. 5. Test Your Heater and Defroster A functioning heater keeps you comfortable, and a working defroster is essential for maintaining visibility. Test both before the first snowfall and have any issues repaired promptly. 6. Keep an Emergency Kit in Your Car Prepare for unexpected situations by keeping a winter emergency kit in your vehicle. Include: A blanket or extra warm clothing Ice scraper and snow brush Flashlight and extra batteries Jumper cables Sand or kitty litter for traction First-aid kit Non-perishable snacks and bottled water Phone charger 7. Check Your Lights and Wipers Shorter days and snowy conditions mean you’ll rely more on your headlights. Ensure all exterior lights are working and replace any burned-out bulbs. Install winter-rated windshield wipers and top off your washer fluid to maintain visibility. 8. Keep Your Gas Tank at Least Half Full A full tank can prevent your fuel lines from freezing and ensure you have enough gas in case of an emergency. Plus, extra weight can help improve traction. 9. Know Your Vehicle’s Winter Features Many modern vehicles come equipped with traction control, ABS, and all-wheel drive. Understand how these systems work to maximize their effectiveness in slippery conditions. 10. Schedule a Winter Maintenance Check at Legacy Automotive The best way to ensure your vehicle is winter-ready is to have it inspected by a professional. At Legacy Automotive, we offer comprehensive winter maintenance services, including battery testing, tire checks, brake inspections, and fluid top-offs. Schedule an appointment today and drive with confidence this winter. Stay safe on the roads and enjoy a worry-free winter with a properly maintained vehicle!
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