by Jim Kerr

Methylcyclopentadienyl Manganese Tricarbonyl. Please don’t ask me to say it! This fuel additive is better known as MMT (for obvious reasons) and if you drove your vehicle today, you most likely used some of it. MMT was first used in Canada in 1977 to boost the octane rating of unleaded gasolines, and over the decades, it has had its share of controversy. Now a new study by the Canadian and US automotive industry has brought the issue of its use into the forefront again.

There are several reasons to be concerned about MMT. Environmentalists are concerned about manganese from the MMT being emitted into the atmosphere. As an element, Manganese is not biodegradeable, so it will accumulate in the soil and air over time. Health advocates note that high doses of airborne manganese can impair both speech and movement. The symptoms are similar to Parkinson’s Disease. Finally, the auto industry blames MMT for degrading emissions components on vehicles and decreasing fuel economy.

On the other side of the fence, the proponents of MMT defend its usage by claiming others use partisan and inconclusive studies. Petroleum companies have shown that MMT is an octane enhancer. Without it, the fuel could self-ignite easier in the engine’s combustion chambers and engine-damaging detonation would occur. In 1978, Health and Welfare Canada reviewed health implications of MMT and concluded there was “no evidence at present to indicate that expected ambient manganese concentrations would constitute a hazard to human health”.

While MMT has support, there are alternatives to using MMT. Several other additives, including alcohol, can increase the octane rating of gasoline, and are much more environmentally friendly. Additional refining of the fuel will increase the octane rating. Unfortunately, other additives or more refining is more expensive than using MMT, so to keep fuel costs down, the fuel companies want to keep using it.

In the US, MMT was banned until 1995 when a court forced the Environmental Protection Agency to approve it for sale. Even then, the majority of fuel companies are still not using it and some states still ban its use! Canada also tried to restrict MMT use. In 1997, the importation of MMT into any province was made illegal. Because MMT is not manufactured in Canada, this effectively banned its use. However, using the Free Trade Agreement, Ethyl Corporation fought this legislation and in 1998, the Canadian Government allowed it back into our fuel.

However, let’s get back to the latest research by the automotive industry and how it affects our vehicles. This study, which is the largest and most comprehensive MMT test program ever conducted, showed that 7 out of 8 low emission passenger cars failed emissions tests when using fuel with MMT over time. Most of the failures were because of excessive HC (hydrocarbon) emissions. When compared to vehicles fuelled without MMT additive, vehicles with MMT had 31% more HC emissions when tested after driving 160,000 km. That is not all.

Oxides of nitrogen (NOx) emissions were 24% higher. Carbon Monoxide (CO) emissions were 14% higher, and Carbon Dioxide (CO2) emissions were 2 per cent higher. Even if one was not concerned about the environmental impact, you should be aware of the cost to vehicle owners in decreased fuel economy and increased maintenance.

On the road, drivers of high mileage vehicles would expect 2 per cent lower fuel economy. Emission components such as oxygen sensors, and catalytic converters become coated with MMT, reducing their efficiency. Spark plugs need to be changed more frequently.

It is estimated that the true cost of replacing MMT with other additives would cost drivers an average of five dollars annually. Compare that to the much higher cost of replacing a set of sparkplugs early or replacing an oxygen sensor.

Canadian automakers are building cars capable of reducing smog-causing emissions by over 99 per cent when compared to vehicles built before controls, but this is hampered by MMT. The auto industry is asking the Canadian Government to restrict the use of MMT again.

The battle between the automotive manufacturers and the oil companies on the use of MMT is far from over. The only positives of MMT are increased fuel octane and low cost. There are alternatives, and given what little we know about long term health effects, and what we do know about increased vehicle maintenance, why not use them?

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