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Jul 13, 2005
New Hampsha
Ok..I have never really noticed it around my area except on military all the Exxon and Mobil stations around me now have a new sticker saying that gas contains MTBE...

I'm a little naive on the stuff other than I know it is bad news if it gets into your water supply.

Bottom line answer I'm looking for- does it affect MPG, in other words give you worse mpg as compared to gas that does not contain MTBE

So far I've noticed considerably worse gas mileage with all oxygenated gas, no matter if the oxygenate was MTBE or ethanol. I'm talking about a drop from 25 mpg to under 20 mpg. Oxygenated gas may burn cleaner, but at least my last two cars showed increased consumption. I think it depends on the engine whether or not you will feel any detrimental effect of oxygenated gas. Not everybody notices a gas mileage decrease. MTBE has been banned in CA due to health concerns. It's been phased out completely by now, I think.
MTBE causes more problems than it cures. Oxygenated gas is not really needed with the modern feedback EFI systems. Part of the gas price problems is that every area has regulations that require a different blend of designer gas. Fuel mileage suffers and emissions per mile are probably not reduced.

We need standardized fuel for the whole US, without the oxygenates.
I will take an MTBE blend over alcohol any day. Eth is a solvent, and has an affinity for water. MTBE is manufactured by the petroleum industry with current hardware and technology. Eth kills throttle response for those who need it.. track days, kart, or MX racing. Politicians, ranchers and farmers are in constant debate over whether to grow corn for people, cattle or fuel. My vote goes to MTBE in the fuel, and E85 for those who have a green thumb. Here is a snippet that gives more info.
In NJ we've had MTBE oxygenated gas for a longtime, first just in the winter time only then all year round. With my 2002 F-150 I get 16mpg on the highway with "NJ" gas and will get 21 mpg using "NON OXYGENATED" gas driving the same way and distance. Areas of PA don't have oxygenated gas. So I've been able to do same day roundtrip driving comparisons of NJ oxygentated and PA non oxygenated gas. I still don't know how burning more gas to go the same distance is good for the environment
? I understand that the republik of New Jerseytan is going to ethanol and higher gas taxes shortly, lucky us
. Lower mpg and more $$$ for this p*ss gas

" MTBE has been banned in CA due to health concerns. It's been phased out completely by now, I think."

and Ca. is the state that started the whole MTBE craze. Think about how bad it must be for them to ban it. Many cities/states followed along after CA. instituted using it, and now several small towns in CA had to have their entire water supply trucked in for a while because MTBE does not break down as readily as straight gas in the soil like they thought it would and it is a known carcinogen IIRC. MTBE is nasty stuff. So if the East coast is just now starting to use this junk, they must really have their heads up their respective rear ends. Any politician/agency moron that requires the use of this stuff needs to be strung up by the nearest light pole. And it does leesen fuel economy to boot. So now you can get less mpg, and be exposed to even more and more dangerous health hazards that cannot be filtered out of the drinking supply to boot. Go down and thank you local chief.
Most states that have used have totally banned its use as well thanks to the California results. It is banned from use in like 29 states now I think I read. Need to do a web search for verification ....
1999 initial study

all the fact may not be right, lots to research here.
but :
· MTBE and other oxygenates were found to have no significant effect on exhaust emissions
from advanced technology vehicles. There is no significant difference in the emissions
reduction of benzene between oxygenated and non-oxygenated CaRFG2 that meets all other
CaRFG2 standards. Thus, there is no significant additional air quality benefit to the use
of oxygenates such as MTBE in reformulated gasoline, relative to alternative CaRFG2
non-oxygenated formulations.
from above study from UC Davis:
There are significant risks and costs associated with water contamination due to the use of
MTBE. MTBE is highly soluble in water and will transfer readily to groundwater from
gasoline leaking from underground storage tanks, pipelines and other components of the
gasoline distribution system.
· In addition, the use of gasoline containing MTBE in motor boats, in particular those using
older 2-stroke engines, results in the contamination of surface water reservoirs. We are
placing our limited water resources at risk by using MTBE. If MTBE continues to be used at
current levels and more sources become contaminated, the potential for regional degradation
of water resources, especially groundwater basins, will increase. Severity of water shortages
during drought years will be exacerbated. We believe that the use of either non-oxygenated
reformulated gasoline or ethanol as an oxygenate in CaRFG2 would result in much lower risk
to water supplies, lower water treatment costs in the event of a spill, and lower monitoring
Economic analysis of the benefits and costs associated with three gasoline formulations:
1. CaRFG2 without added oxygenate
2. CaRFG2 with ethanol
3. CaRFG2 with MTBE
indicates that non-oxygenated gasoline achieves air quality benefits at the least cost, followed
by CaRFG2 with ethanol. CaRFG2 with MTBE has the highest net annual cost due primarily
to the costs of treating contaminated water supplies, higher fuel prices, and lower fuel
The summary and complete report will be made available on the Internet at

The above report is what led Gov Davis to order the phasing out of the use of MTBE for oxygnated fuel in Ca, first by March 15, 2002 then extended to dec 31, 2003.
MTBE is banned in many states right now. I like ethanol blends as the ethanol keeps my fuel system clean.
There are no human data on which an evaluation of the carcinogenicity of MTBE can be
based. However, substantial evidence from studies of chronic exposure by either oral or
inhalation routes demonstrtate that MTBE is carcinogenic in rats and mice. Based on a thorough
review of these carcinogenicity studies, supporting data on pathology and mechanisms of tumor
induction, and carcinogenicity studies of MTBE's primary metabolites (TBA and formaldehyde),
we conclude that MTBE is an animal carcinogen with the potential to cause cancer in humans.

From: An Evaluation of the Scientific Peer-Reviewed
Research and Literature on the Human Health
Effects of MTBE, its Metabolites, Combustion
Products and Substitute Compounds
John R. Froines, Ph.D.
Principal Investigator
Michael Collins, Ph.D.
Elinor Fanning, Ph.D.
Rob McConnell, M.D.
Wendie Robbins, Ph.D.
Ken Silver, M.S.
Heather Kun
Rajan Mutialu
Russell Okoji, MSPH
Robert Taber, M.D., MPH
Naureen Tareen, MPH
Catherine Zandonella
found at :
as aprt of the executive summary, most of the report on effects is that there is not enough data for many of the areas, but finding show warrant for further study.
very detailed paper and very informative.
And the states collect gasoline taxes even on the oxygen component of the fuel. They've found a way to tax air.

Gasoline itself is probably more carcinogenic than MTBE. It's also responsible for many deaths due to fire after a vehicle crash. Diesel fuel does not ignite so easily.
Ah, but the point is that gasoline does break down and generally does not build up in the water supply over time. MTBE resists biodegration and has been found in ground water.
Get used to ethanol in your gas, kids. It may be controversial for the time being as an oxygenator, but, unless we find incredibly large petroleum pools on these shores soon, corn squeezins may well be the primary, renewable gasoline extender for the foreseeable future.
Ray, it is more then just corn they make ethanol from. Look at Brazil. They make enough ethanol from sugar cane that they are able to export some of their oil.
MTBE was banned because it was showing up in ground water samples. MTBE is not soluble in water and is very cheap and easy to detect in water therefore it was being found quickly and cheaply. This was not due to auto emissions but rather to leaky storage tanks. So rather than have the oil industry spend billions fixing their problem Califoria bans MTBE in favour of Iso-octane which is much harder to detect in water. Its still there though. So we the tax payers will foot the bill very soon for the clean-up not the gas station owners. Methyl-tertiary-butyl-ether wasn't a bad product or additive in fact we used to use pure MTBE in the company trucks when the boss wasn't looking.
I think MTBE helps only if your car is running in open loop (before warm up) and in very cold weather. However, if your car is that old and is not running correctly, our SMOG check (on a dyno at 25mph) will definitely catch you.
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