09/11/2026
⛽ DUNE GOON DAILY NEWS ⛽
Thursday, September 10, 2026
WHAT'S IN YOUR TANK, GOONS? THE AVGAS TRUTH
Fuel is all over the headlines right now. The FAA just dropped its final plan to move airplanes off leaded 100LL avgas by the end of 2030. Meanwhile E15 has been showing up at way more pumps this year thanks to EPA emergency waivers, and the House passed a bill in May to allow it year round. Translation: the two fuels we argue about most around the fire are both changing. So let's separate the campfire rumors from the facts.
THE INTERNET RUMORS
RUMOR: "Avgas fouls your plugs and cakes your valves."
TRUTH: Lead deposits are real chemistry, but they build up when an engine idles cold and putts around. A machine that gets ridden hard runs hot enough to push the lead byproducts right out the pipe. I've run 100LL in both my CRF450Rs since 2021. Five years, zero plug problems.
RUMOR: "Avgas burns hotter and will melt a piston."
TRUTH: Octane measures knock resistance, not heat. Higher octane does not make a hotter fire. Detonation is what actually kills pistons, and 100LL has about 100 octane worth of protection against it.
RUMOR: "More octane means more power."
TRUTH: Only if the engine is built or tuned to use it. On a stock machine, octane beyond what the manual calls for adds zero ponies. It just keeps you safe from knock.
RUMOR: "Avgas will wreck anything you put it in."
TRUTH: Half true, and it depends entirely on what's bolted to your exhaust. Lead permanently poisons catalytic converters and coats O2 sensors. If your machine has a cat, a steady diet of avgas slowly kills it. If it doesn't, the lead has nothing to hurt.
RUMOR: "Avgas is junk fuel with no additives."
TRUTH: It's actually one of the most tightly controlled fuels you can buy. Ethanol free, low aromatics, consistent batch to batch, and built to sit in a tank without going bad. The only true part: it doesn't have the detergent package pump gas has.
MY REAL WORLD TEST
Two CRF450Rs, a Raptor 700, and every generator I own have been on 100LL for years. No plug fouling, no O2 sensor issues on the 450s, and stuff honestly lasts longer than it did on cheap pump gas. I also ran a full pail of VP T4 race fuel through one of the 450s back to back with avgas. Felt zero difference.
THE REAL FACTS ON 100LL
• About 100 octane. Plenty for a high compression 450.
• Zero ethanol. No water absorption, no phase separation, no varnish in your carb or injectors when it sits.
• Long shelf life. Huge for machines that sit between trips.
• A bit lighter per gallon than pump gas, so a hair less energy. Some guys richen the fueling a click after switching.
• Lower v***r pressure. Cold starts can be lazy on a freezing morning. Once it's warm, no difference.
• Illegal in street vehicles. Federal law bans leaded fuel in on road motor vehicles. Keep it out of the truck.
• It's on the clock. With the FAA pushing to end leaded avgas by 2030, don't count on it being around forever.
MACHINE BY MACHINE
✅ QUADS AND DIRT BIKES WITH NO CAT: Carbed or fuel injected doesn't matter if there's no catalytic converter for the lead to poison.
✅ MX BIKES LIKE THE CRF450R: US models are closed course race bikes with no cat. They do have an O2 sensor, but ridden hard it stays hot and clean. Five years on mine and it's still happy.
✅ GENERATORS AND ANYTHING THAT SITS: This is where avgas might be the BEST choice. Old ethanol gas sitting in a carb bowl is how small engines die. Avgas fixes that exact problem.
🛑 STOCK SIDE BY SIDES WITH A CAT: Machines like the Can-Am X3 come from the factory with a catalytic converter and O2 sensor. One mixed tank won't hurt anything, but as a regular fuel it slowly kills the cat and sensor. Stick with unleaded. If your machine is cat deleted and tuned, talk to your tuner about fuel.
🛑 ANYTHING STREET LEGAL: Not happening.
Not sure what your machine has? Look at the exhaust before you pour.
THE BEST FUEL TYPES, RANKED
1. Ethanol free unleaded race fuel (VP T4, Sunoco Optima, Renegade Pro Unleaded). Safe for everything, including side by sides with a cat. Stable in storage and consistent. Only downside is the price tag.
2. Ethanol free premium pump gas (91 or 92). Best bang for the buck in any machine. Buy it fresh and burn it.
3. 100LL avgas. The champ for bikes, quads, and generators with no cat, especially anything that sits. Not for cat equipped side by sides or anything street legal.
4. E10 premium. Fine if it's fresh from a busy station and gets burned within a couple weeks. Worst choice for anything that sits.
5. E15 (sold as Unleaded 88 or UNL88). Hard no. It's not approved for motorcycles, off road vehicles, or small engines. With E15 at more stations this year, read the pump label before you fill your cans.
HONORABLE MENTIONS
• Leaded race gas (like VP MR12): made for high compression builds and aggressive tunes. On a stock machine you're paying more for nothing.
• E85: only in a machine tuned for it. Popular in big turbo side by side builds, never in a stock one.
RULE OF THUMB: Always run at least the octane your owner's manual calls for. More than that won't make a stock machine faster.
GOON BOTTOM LINE
Most of the avgas horror stories online come from people applying car rules to machines that don't have car parts. No cat and ridden hard? Avgas is great fuel. Got a cat? Stay unleaded. Got a can of E10 that's been sitting in the garage since last season? That's the real enemy.
United by Sand. 🏜️