[vertigto]

I've only run non-ethanol fuel in my GTO, but didn't realize that it is a no-no (per the article below} and can foul the fuel system with a brown sludge if the non-ethanol fuel contains MTBE. Supposedly, only off-road stations/marinas are supposed to sell it, but I'm not convinced since reading that most of the non-ethanol with MTBE is in the Southeast.

Is this true and a valid concern? Has anyone mixed and experienced the issues mentioned in the article. I will confess that I have once put non-ethanol in my Ram which usually only gets 91 or 93 (E10).

https://www.bellperformance.com/blog/how-likely-will-you-find-mtbe-where-you-are

The Clean Air Act of 1992 was a major step taken by Congress to change behavior in order to better the environment. One of the results of this and subsequent legislation was the inclusion of "oxygenates" into the gasoline supply across the nation, which add more oxygen to gasoline, making it burn cleaner and making it better for the environment.

Ethanol hasn't always been the "oxygenate of choice" to satisfy the Clean Air Act. Initially, that choice was MTBE and millions of gallons per day were produced and mixed into gasoline at its peak in the 1990s. But fears of groundwater contamination causes most states to remove it from the on-road fuel supply in favor of ethanol. Remember, whatever they were going to use on a widescale had to be inexpensive to produce and easy to transport across long distances. Ethanol met both of these criteria.

Today, you won't find MTBE in any on-road gasoline, but you can find it in marine fuels (considered off-road). Off-road fuels like marine gas aren't subject to the same kinds of regulations that on-road fuels are.

Why Does This Matter?
If you don't ever use off-road gasoline for things like boats or small equipment, then none of this really matters for you. But for people who do (have to use off-road gas), they have to be aware of the possible chemical interactions between ethanol and MTBE if they happen to mix gasoline containing either one. And nobody intends to make this mistake, but life gets in the way of the best intentions sometimes. Maybe they couldn't get ethanol-free gas for their boat one time, and so they fill up with E10 on top of the little bit of pure gas left in the tank. When this happens, a brown sludge forms from the chemical interaction and it gums up all parts of the engine and fuel system. There's no additive for fuel that can keep this from happening. The only way to stop it is not to let it happen in the first place by mixing fuels inadvertently.

How Do I Know If My Gas Has MTBE?
First, remember that we're talking about off-road gas here, not the on-road gas for your car and truck. But the bottom line here is that you don't know for sure if any off-road gas really has MTBE. It's not like anyone advertises it. Many states have tried to phase MTBE out of even marine gas, but there's still a certain amount of it floating around.

Where are you most likely to find it?
The Southeast and Coastal states. This leads to the question of why MTBE is more likely to still be present in off-road gas in these states. The answer has to do with proximity to production and transportation costs.

Because of the nature of ethanol, it can't be transported by pipeline like MTBE can. Fuel suppliers pretty much have to blend it online at the fuel terminal. So ethanol can't travel by pipeline, which means it has to go by railcar or tanker truck. So the further away it has to be hailed by road or rail, the more expensive it becomes. Where is the majority of mass ethanol production done in this country? The Midwest, where all the corn is.

So the simple reason why you're more likely to find MTBE in coastal states is that they're the furthest away from ethanol production and thus the most expensive to supply ethanol to. It has to be supplied for on-road gasoline, but if they can put something else into off-road gasoline, they will. Like MTBE.

Last question - if off-road gasoline isn't subject to the same oxygenate requirements as regular on-road gas, why are ethanol and MTBE even put in? Short answer - because they have also traditionally been used to help make up the octane value of gasoline. They may not need to make off-road gas cleaner burning, but it still has to have adequate octane value.

Bottom Line
The bottom line here is this. If you use off-road gasoline, and you can't be sure that the gas you're using does or does not contain MTBE, err on the side of caution and make sure you don't mix ethanol-free and E10 or E15 gas. You could be sorry if you make that mistake.

[Formulabruce]

1. MTBE is a by product of making gasoline.
2. MTBE is much more dense than ethanol which , given same octane, and fuel amount, will give more power.
3. Ethanol doesn't really mix with gasoline well. You can easily separate it out.
4. MTBE is Not considered a combustible agent in gas, its a added " filler" which keeps fuel density and burns up the otherwise wasted MTBE ( or parts thereof).
5. Ethanol will not blend with it well, but keep in mind it doesn't stay blended in gasoline either without stabilizing agents.

[vertigto]

So...if you run a tankful of ethanol gas and next fill up use ethanol-free gas (assuming containing MTBE) with the small amount of inevitable mixing of the two, there is no risk in developing any of this so-called 'brown sludge'?

I can see the possibility of running low on gas in the GTO and not being able to find an ethanol-free station, unless carefully planned. If this is not an issue, I won't lose any sleep.

[Stuart]

The problem with e10 is when you let it sit in the car unused for long periods, and then it gums up your carburetor. If you're driving the car and using it up, I don't think you'll have any issues.

[61-63]

I'm not sure e10 gums up anything. I've got a 389 test stand engine I've been flow testing carburetors on for probably twenty years now. The carburetor that sits on it permanently to keep the battery hot during periods that it sits for awhile is an AFB that I restored when I originally did a cheap rebuild on this engine and put it on my test stand.
During the not running intervals the fuel has evaporated out of the float bowls of that AFB over and over and over; dk how many times but during twenty years lt's a bunch. I have a marine gas tank and pump bulb on my test stand and refill the dry float bowls with the pump bulb before starting the engine after every gap of three or four days without running which is about what it takes for the float bowls to dry out. That "permanent" AFB has never been rebuilt and works fine, the engine starts up zip-pop every time, idles fine, the engine jumps if I blip the throttle. I haven't taken that carb apart in twenty years but I guarantee you if I did I wouldn't find it to be gummed up.

[Formulabruce]

For many reasons of deign ( None are fuel economy FYI) the AFB seems to handle the evap situation very well as its simple and not a factory carb used for fuel economy.
Brown sludge will only occur if partial evap occurs with MTBE and E10 after say 4-5 months. This is more part of separation.
Carbs with more passages and more fuel controls always have more issues with sitting with almost any fuel.

[GT182]

I've mixed 5 gallons of either Sunoco or VP C9 (93 unleaded) with half a tank of 87 E10 in the GTO. No issues at all. No issues even running just the 87 E10.

[roger1]

Only a guess but I think ethanol-free gas probably contains ETBE as an oxygenator in place of MTBE. And, I'm guessing that doesn't have an issue mixed with the ethanol in E10.

[GT182]

I have no idea if ethanol fuel contains MTBE or not. This is the first I've ever heard of it. I know the C9 is good stuff as I also use it in my push mower, 4 cycle trimmer, and blower vac. They don't start very well, or not at all with E10 gas.

[necdb3]

I've been mixing 100LL with 93 pump gas with no issues. Not sure of any gasoline with MTBE any longer.

[fyrffytr1]

I have been running non-ethanol gas in my 67 for well over ten years now and have never had a fuel issue. My car may sit for two or three weeks but it always cranks up and runs fine.

[Tom Vaught]

Originally Posted by fyrffytr1

I have been running non-ethanol gas in my 67 for well over ten years now and have never had a fuel issue. My car may sit for two or three weeks but it always cranks up and runs fine.

Many Farmers in the northern counties of Michigan use gasoline that has no ethanol in the fuel. Tractors, combines, etc use the stuff in their on the farm storage tanks and the gas truck tops off the farm tanks throughout the farm season.

I run the non-ethanol gas in my GTO because the station is only a few miles from my home.

Tom V.

[hurryinhoosier62]

We had non ethanol 90 octane all over FL when we lived there. The marine industry was dying on ethanol enriched fuel, so EPA relented after being sued by marine engine manufacturer in federal court. Odd thing; in central FL 100LL is commonly available for airboat owners still running aircraft recip engines in their airboats, but don’t think you can fill up your muscle car with it. The FL tax agents will be more than happy to write you a ticket and a summons to appear in court and explain WHY you are running non-road taxed fuel in your highway driven vehicle.

[Tom Vaught]

The Marathon gas station in Armada Michigan sells "No Ethanol" and 15% ethanol at separate pumps. They also sell E85 fuel. But no race gas. About $3.80 per gallon on average. A "24 PUMP" STATION.

Tom V.